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Estimate a derivative at a point

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53234712
The graph of \(f\) is shown with tangent lines \(t_1\) at \(A(0,2)\) and \(t_2\) at \(B(4,2)\). a) Use the tangent lines to find \(f'(0)\) and \(f'(4)\). Briefly explain your method. b) Decide whether the derivative is positive, negative, or zero at each input. Briefly justify each answer. 1) \(x=2\) 2) \(x=5\) 3) \(x=-2\)
Figure for problem 532347

Hints

- A derivative value equals the slope of the tangent line. - Use two exact points on each tangent to calculate its slope. - Increasing, decreasing, and horizontal behavior correspond to positive, negative, and zero derivative values.

Solution

1. The line \(t_1\) passes through \(A(0,2)\) and \((-2,0)\). Its slope is \(\frac{2-0}{0-(-2)}=1\), so \(f'(0)=1\). 2. The line \(t_2\) passes through \(B(4,2)\) and \((6,0)\). Its slope is \(\frac{0-2}{6-4}=-1\), so \(f'(4)=-1\). 3. At \(x=2\), the graph has a local maximum and a horizontal tangent, so \(f'(2)=0\). 4. At \(x=5\), the graph is decreasing, so \(f'(5)<0\). 5. At \(x=-2\), the graph is increasing, so \(f'(-2)>0\).

Answer

a) \(f'(0)=1\) and \(f'(4)=-1\) b) 1) \(f'(2)=0\) 2) \(f'(5)<0\) 3) \(f'(-2)>0\)
53235312
The graph of \(f\) is shown. Decide whether each statement about \(f'\) is true or false, and briefly justify your answer. A) At \(x=0\), the derivative is positive because the graph passes through the origin. B) \(f'(-2)=0\) and \(f'(2)=0\). C) For every \(-2<x<2\), the graph of \(f'\) lies below the x-axis. D) The graph of \(f'\) is a downward-opening parabola.
Figure for problem 532353

Hints

- The derivative represents the slope of the graph at each input. - Relate increasing and decreasing behavior to the sign of the derivative. - At a smooth local maximum or minimum, the tangent is horizontal. - Compare the derivative's sign pattern with the opening direction of a parabola.

Solution

1. A is false. At \(x=0\), the graph of \(f\) is decreasing, so \(f'(0)<0\). Passing through the origin does not determine the derivative sign. 2. B is true. The graph has a local maximum at \(x=-2\) and a local minimum at \(x=2\), so both tangent lines are horizontal. 3. C is true. The function decreases throughout \((-2,2)\), so \(f'(x)<0\) on that interval. 4. D is false. The derivative is positive outside the two zeros and negative between them, which matches an upward-opening parabola.

Answer

A) False; \(f'(0)<0\) because \(f\) is decreasing there. B) True; both inputs are smooth extrema. C) True; \(f\) is decreasing on \((-2,2)\). D) False; the sign pattern matches an upward-opening parabola.
53235512
The figures show the graph of a function \(f\) (Figure 1) and the graph of its derivative \(f'\) (Figure 2). Use the graphs to determine: a) \(f(2)\), b) the slope of the graph of \(f\) at \(x = -1\), c) one value \(a\) for which \(f(a) = 1\), d) all values \(b\) at which the graph of \(f\) has slope \(3\).
Figure for problem 532355

Hints

- Decide which graph gives function values and which gives slopes. - The derivative value \(f'(x)\) is the slope of \(f\) at \(x\). - For part c), find an \(x\)-coordinate where the graph of \(f\) has height \(1\). - For part d), find where the derivative graph has value \(3\).

Solution

1. Read the function value from Figure 1: \(f(2) = -1\). 2. The slope at \(x = -1\) is \(f'(-1)\). Figure 2 gives \(f'(-1) = -1.5\). 3. In Figure 1, the graph passes through \((0, 1)\), so one possible value is \(a = 0\). 4. A slope of \(3\) means \(f'(b) = 3\). Figure 2 shows this at \(b = -2\) and \(b = 2\).

Answer

a) \(f(2) = -1\) b) The slope is \(-1.5\). c) \(a = 0\) d) \(b = -2\) and \(b = 2\)
53236212
The graph of \(f\) is shown with points \(A\), \(B\), and \(C\) and their tangent lines in orange. Use the graph to find the equation of the tangent line at each point.
Figure for problem 532362

Hints

- A tangent line touches the curve at the marked point and has the same local direction there. - Use the slope-intercept form of a line. - Read the y-intercept directly when possible. - Use two grid points to calculate each nonzero slope. - What is the slope of a horizontal line?

Solution

1. At \(A(0,2)\), the tangent also passes through \((1,3)\). Its slope is \(\frac{3-2}{1-0}=1\), and its y-intercept is \(2\). Thus, the tangent line is \(y=x+2\). 2. At \(B(2,3)\), the tangent is horizontal. Its slope is \(0\), so its equation is \(y=3\). 3. At \(C(4,2)\), the tangent also passes through \((5,1)\). Its slope is \(\frac{1-2}{5-4}=-1\). Using \((4,2)\), the line is \(y-2=-(x-4)\), or \(y=-x+6\).

Answer

At \(A\): \(y=x+2\) At \(B\): \(y=3\) At \(C\): \(y=-x+6\)
53242012
The first coordinate plane shows the graph of \(f\). The other three planes show graphs \(A\), \(B\), and \(C\). One of them represents \(f'\). Which graph is \(f'\)? Justify your choice.
Figure for problem 532420

Hints

- Find the inputs where \(f\) has horizontal tangents. - The derivative is zero at those inputs. - Determine where \(f\) is decreasing. - The derivative must be negative on decreasing intervals.

Solution

1. The graph of \(f\) has a local maximum at \(x=-2\) and a local minimum at \(x=2\). Therefore, \(f'(-2)=0\) and \(f'(2)=0\). This eliminates graph \(C\), which has only one zero. 2. The graph of \(f\) decreases between \(-2\) and \(2\), so \(f'(x)<0\) on that interval. 3. Graph \(A\) is below the x-axis between its zeros at \(-2\) and \(2\), while graph \(B\) is above the x-axis there. Therefore, graph \(A\) represents \(f'\).

Answer

Graph \(A\) represents \(f'\).
53242112
The graph of \(f\) is shown with four candidate graphs, \(A\), \(B\), \(C\), and \(D\). Which candidate represents \(f'\)? Justify your choice by comparing key features.
Figure for problem 532421

Hints

- Locate the horizontal tangents of \(f\). - The derivative has zeros at those x-coordinates. - Determine where \(f\) is increasing and decreasing. - Eliminate candidates using both zeros and sign.

Solution

1. The graph of \(f\) has a local maximum at \(x=-1\) and a local minimum at \(x=3\). Thus, \(f'(-1)=0\) and \(f'(3)=0\). This eliminates \(C\), whose zeros are different, and \(D\), which has only one zero. 2. The function decreases between \(-1\) and \(3\), so \(f'(x)<0\) on that interval. 3. Only graph \(A\) has zeros at \(-1\) and \(3\) and is negative between them. Therefore, graph \(A\) represents \(f'\).

Answer

Graph \(A\) represents \(f'\).
53252612
The graph of \(f\) is shown. Answer each question about \(f'\) by reading and reasoning from the graph. a) Find the zeros of \(f'\). Briefly explain your method. b) Give the interval on which the graph of \(f'\) lies above the x-axis. c) Estimate \(f'(0)\) by estimating the tangent slope at \(x=0\).
Figure for problem 532526

Hints

- Where does the graph of \(f\) have horizontal tangents? - Relate increasing behavior to a positive derivative. - Estimate a curve's slope by imagining a tangent line and a slope triangle. - Use convenient nearby points for the estimate.

Solution

1. The graph of \(f\) has a local minimum at \(x=-1\) and a local maximum at \(x=1\). Therefore, the zeros of \(f'\) are \(x=-1\) and \(x=1\). 2. The graph of \(f\) increases between the two extrema, so \(f'(x)>0\) for \(-1<x<1\). 3. At \(x=0\), a reasonable tangent estimate uses \((0,1)\) and approximately \((1,2.5)\), giving \(f'(0)\approx\frac{2.5-1}{1-0}=1.5\). Estimates from about \(1.3\) to \(1.7\) are reasonable from the graph.

Answer

a) \(x=-1\) and \(x=1\) b) \((-1,1)\) c) \(f'(0)\approx1.5\)
53253412
The graph of a quadratic function \(f\) and its tangent lines \(t_1\) and \(t_2\) at points \(A\) and \(B\) are shown. Use convenient grid points to find the equations of \(t_1\) and \(t_2\). Then find the angle of inclination of each tangent line to the nearest tenth of a degree.
Figure for problem 532534

Hints

- Choose two exact grid points on each tangent line. - Use the slope formula with the two points. - The slope and angle of inclination satisfy \(m=\tan(\alpha)\). - Use the inverse tangent function on a calculator to find each angle.

Solution

1. The line \(t_1\) passes through \(A(0,-1)\) and \((1,0)\). Its slope is \(m_1=\frac{0-(-1)}{1-0}=1\), so \(t_1\) is \(y=x-1\). 2. The line \(t_2\) passes through \(B(2,3)\) and \((1,0)\). Its slope is \(m_2=\frac{3-0}{2-1}=3\), so \(t_2\) is \(y-3=3(x-2)\), or \(y=3x-3\). 3. Since \(m=\tan(\alpha)\), \(\alpha_1=\arctan(1)=45.0^\circ\). 4. Similarly, \(\alpha_2=\arctan(3)\approx71.6^\circ\).

Answer

\(t_1: y=x-1\), with \(\alpha_1=45.0^\circ\) \(t_2: y=3x-3\), with \(\alpha_2\approx71.6^\circ\)
53257612
A differentiable function \(f\) is strictly increasing for \(x<-1\) and \(x>3\), and strictly decreasing for \(-1<x<3\), within the displayed interval \([-4,4]\). Which graph, I, II, or III, could represent \(f'\)? Justify your answer.
Figure for problem 532576

Hints

- Relate monotonicity of \(f\) to the sign of \(f'\). - Identify where the monotonicity changes. - The derivative should have zeros at those transition inputs. - Check whether each candidate is above or below the x-axis on each interval.

Solution

1. Since the monotonicity changes at \(x=-1\) and \(x=3\), the derivative must be zero there and change sign at each point. 2. Graphs I and II have zeros at \(-1\) and \(3\). Graph III has different zeros, so it cannot represent \(f'\). 3. Because \(f\) increases for \(x<-1\) and \(x>3\), the derivative must be positive in those regions. Because \(f\) decreases for \(-1<x<3\), the derivative must be negative there. 4. Only graph I has this sign pattern. Therefore, graph I could represent \(f'\).

Answer

Graph I could represent \(f'\).
53263412
The graph of a function \(f\) and its tangent line \(t\) at the origin are shown. Use the graph to determine: a) the zeros of \(f^{\prime}\), b) the value of \(f^{\prime}(0)\), and c) the interval on which \(f^{\prime}(x)<0\).
Figure for problem 532634

Hints

- Look for points where the graph has horizontal tangent lines. - The derivative at a point is the slope of the tangent line there. - Use two points on line \(t\) to calculate its slope. - The derivative is negative where the function is decreasing.

Solution

1. The zeros of \(f^{\prime}\) occur where the graph of \(f\) has horizontal tangent lines. The graph has a local maximum at \(x=-3\) and a local minimum at \(x=3\), so the zeros are \(x=-3\) and \(x=3\). 2. The value \(f^{\prime}(0)\) is the slope of tangent line \(t\). The line passes through \((0,0)\) and \((2,-3)\), so its slope is \(\frac{-3-0}{2-0}=-1.5\). Therefore, \(f^{\prime}(0)=-1.5\). 3. The graph of \(f\) decreases between the local maximum and local minimum. Therefore, \(f^{\prime}(x)<0\) for \(x\in(-3,3)\).

Answer

a) \(x=-3\) and \(x=3\) b) \(f^{\prime}(0)=-1.5\) c) \(x\in(-3,3)\)
53266812
The graph shows \(f\) and its derivative \(f'\), where \(f(x) = 0.5x^2 - x + 0.5\) and \(f'(x) = x - 1\). Use the graph to determine: a) the slope of the tangent to \(f\) at \(x = 0\): \(-2\), \(-1\), or \(0\), b) the \(x\)-values where the function value and derivative value are equal.
Figure for problem 532668

Hints

- The derivative value gives the tangent slope. - Equal function and derivative values appear as intersections of the two graphs.

Solution

1. The tangent slope at \(x = 0\) is \(f'(0) = 0 - 1 = -1\). 2. The function value and derivative value are equal where the two graphs intersect. The intersections occur at \((1, 0)\) and \((3, 2)\), so the required \(x\)-values are \(1\) and \(3\).

Answer

a) \(-1\) b) \(x = 1\) and \(x = 3\)
53368512
The graph of \(f\) is shown. Which statements about the derivative \(f^{\prime}\) are true? Justify each decision. (A) \(f^{\prime}(0)=0\). (B) \(f^{\prime}(2)\) is approximately \(-1\). (C) The derivative \(f^{\prime}\) is strictly decreasing throughout the displayed interval. (D) For \(x<0\), the graph of \(f^{\prime}\) lies below the x-axis.
Figure for problem 533685

Hints

- The derivative at an input is the tangent slope there. - A smooth local extremum has a horizontal tangent line. - Use increasing and decreasing behavior to determine the sign of the derivative. - Use concavity to determine whether derivative values are increasing or decreasing.

Solution

1. Statement (A) is true. The graph has a local maximum at \(x=0\), so its tangent line is horizontal and \(f^{\prime}(0)=0\). 2. Statement (B) is true. A tangent-line estimate at \(x=2\) gives a slope of about \(-1\), so \(f^{\prime}(2)\approx-1\). 3. Statement (C) is true. The graph is concave down throughout the displayed interval, so its tangent slopes continually decrease. Therefore, \(f^{\prime}\) is strictly decreasing. 4. Statement (D) is false. For \(x<0\), the graph of \(f\) is increasing, so \(f^{\prime}(x)>0\) and the derivative graph lies above the x-axis.

Answer

(A) True (B) True (C) True (D) False
53369312
The graph of a quadratic function \(f\) is shown. 1) Find the input where the graph of \(f^{\prime}\) crosses the x-axis. 2) Find an equation for the graph of \(f^{\prime}\). Describe how the sign of \(f^{\prime}(x)\) changes at its zero.
Figure for problem 533693

Hints

- The derivative is zero where the original graph has a horizontal tangent line. - Determine where \(f\) is increasing and decreasing. - The derivative of a quadratic function is linear.

Solution

1. The derivative is zero where the graph of \(f\) has a horizontal tangent line. The vertex occurs at \(x=0\), so \(f^{\prime}(0)=0\). 2. The graph of \(f\) is a downward-opening parabola. It increases for \(x<0\), so \(f^{\prime}(x)>0\), and decreases for \(x>0\), so \(f^{\prime}(x)<0\). From the vertex \((0,2)\) and the point \((2,0)\), write \(f(x)=ax^2+2\) and solve \(0=4a+2\), giving \(a=-0.5\). Thus, \(f(x)=-0.5x^2+2\) and \(f^{\prime}(x)=-x\). The derivative graph is a decreasing line through the origin, crossing the x-axis from positive values to negative values.

Answer

1) The zero of \(f^{\prime}\) is \(x=0\). 2) The graph is the line \(y=-x\). The derivative is positive for \(x<0\) and negative for \(x>0\).
53369412
The graph of a translated parabola \(f\) is shown. 1) At what input does the graph of \(f^{\prime}\) cross the x-axis? 2) Use the monotonicity of \(f\) to determine whether \(f^{\prime}(x)\) is positive or negative for \(x>2\).
Figure for problem 533694

Hints

- At the vertex of a smooth parabola, the tangent line is horizontal. - The derivative is positive where the function is increasing.

Solution

1. The graph of \(f\) has its minimum at \(x=2\). The tangent line is horizontal there, so \(f^{\prime}(2)=0\). Thus, the derivative graph crosses the x-axis at \(x=2\). 2. For \(x>2\), the graph of \(f\) is increasing. Therefore, its tangent slopes are positive and \(f^{\prime}(x)>0\).

Answer

1) \(x=2\) 2) \(f^{\prime}(x)>0\) for \(x>2\).
53369512
The graph of \(f\) is shown. 1) Find the x-coordinates where the graph of \(f^{\prime}\) crosses the x-axis. 2) On what interval is \(f^{\prime}\) negative? Justify your answer using the behavior of \(f\).
Figure for problem 533695

Hints

- Locate the local maximum and local minimum. - The derivative is zero where the tangent line is horizontal. - The derivative is negative where the function is decreasing.

Solution

1. The derivative is zero at the local extrema of \(f\). The graph has a local maximum at \(x=-2\) and a local minimum at \(x=2\). Therefore, the derivative graph crosses the x-axis at \(x=-2\) and \(x=2\). 2. The graph of \(f\) is decreasing between the local maximum and local minimum. Therefore, \(f^{\prime}(x)<0\) for \(-2<x<2\).

Answer

1) \(x=-2\) and \(x=2\) 2) \(f^{\prime}(x)<0\) on \((-2,2)\).
53370512
Use the graph to find the equations of the tangent lines to \(f\) at points \(A\), \(B\), and \(C\).
Figure for problem 533705

Hints

- Use the tangent lines' intercepts or other exact grid points to find their slopes and y-intercepts. - For a shallow line, choose grid points that are farther apart to reduce reading error.

Solution

1. At \(A(1,4)\), the tangent passes through \((0,8)\) and \((2,0)\). Its slope is \(\frac{0-8}{2-0}=-4\), and its y-intercept is \(8\). Thus, the line is \(y=-4x+8\). 2. At \(B(2,2)\), the tangent passes through \((0,4)\) and \((4,0)\). Its slope is \(\frac{0-4}{4-0}=-1\), and its y-intercept is \(4\). Thus, the line is \(y=-x+4\). 3. At \(C(4,1)\), the tangent passes through \((0,2)\) and \((8,0)\). Its slope is \(\frac{0-2}{8-0}=-0.25\), and its y-intercept is \(2\). Thus, the line is \(y=-0.25x+2\).

Answer

At \(A\): \(y=-4x+8\) At \(B\): \(y=-x+4\) At \(C\): \(y=-0.25x+2\)
53370712
The graph of a cubic function is shown. Use the graph to find the equations of the tangent lines at points \(A\), \(B\), and \(C\).
Figure for problem 533707

Hints

- A horizontal tangent has an equation of the form \(y=\text{constant}\). - At \(B\), use grid points to estimate how quickly the tangent falls.

Solution

1. At \(A(-2,4)\), the graph has a local maximum, so the tangent is horizontal. Its equation is \(y=4\). 2. At \(B(0,0)\), the tangent passes through the origin and falls \(3\) units for each \(1\)-unit increase in \(x\). Its slope is \(-3\), so its equation is \(y=-3x\). 3. At \(C(2,-4)\), the graph has a local minimum, so the tangent is horizontal. Its equation is \(y=-4\).

Answer

At \(A\): \(y=4\) At \(B\): \(y=-3x\) At \(C\): \(y=-4\)
53371912
The graph of a quadratic function \(f\) is shown. Determine the graph of \(f^{\prime}\), beginning by finding the input where the slope of \(f\) is zero.
Figure for problem 533719

Hints

- Find the horizontal tangent line on the parabola. - Estimate tangent slopes at one or two additional inputs. - The derivative of a quadratic function is linear. - Use the increasing and decreasing intervals to check the sign of the derivative graph.

Solution

1. The graph of \(f\) has a minimum at \(x=2\), so \(f^{\prime}(2)=0\). 2. From the graph, the tangent slope is about \(-2\) at \(x=0\) and about \(2\) at \(x=4\). 3. Since \(f\) is quadratic, \(f^{\prime}\) is linear. The line through \((0,-2)\), \((2,0)\), and \((4,2)\) is \(f^{\prime}(x)=x-2\).

Answer

The derivative graph is the line \(f^{\prime}(x)=x-2\). It crosses the x-axis at \(x=2\) and passes through \((0,-2)\).
53384712
The graph shows a quadratic function \(f\) and its derivative \(f'\), one in red and one in blue. a) Identify which graph represents \(f\) and which represents \(f'\). Justify your answer by comparing important features of the graphs. b) Use the graph to find the equation of the tangent line to \(f\) at \(x=2\).
Figure for problem 533847

Hints

- What value does a derivative have where the original function has a horizontal tangent? - Compare the minimum of one graph with the x-intercept of the other. - The derivative graph gives the tangent slope at each input. - A tangent equation requires both a point on \(f\) and the derivative value there.

Solution

1. The red graph represents \(f\), and the blue graph represents \(f'\). 2. The red graph has a minimum at \(x=0\), where its tangent is horizontal. The blue graph has value \(0\) at \(x=0\), as a derivative must at that critical point. 3. From the red graph, \(f(2)=0\), so the point of tangency is \((2,0)\). From the blue graph, \(f'(2)=1\), so the tangent slope is \(1\). 4. The line through \((2,0)\) with slope \(1\) is \(y=x-2\).

Answer

a) The red graph is \(f\), and the blue graph is \(f'\). The derivative is zero at the x-coordinate of the minimum of \(f\). b) \(y=x-2\)
53384812
The graph shows a periodic function \(f\) and its derivative \(f'\), one in green and one in orange. a) Identify which graph represents \(f\) and which represents \(f'\). Justify your answer. b) Use the graphs to find the equation of the tangent line to \(f\) at \(x=0\).
Figure for problem 533848

Hints

- Compare the x-intercepts of one graph with the maxima and minima of the other. - The derivative is zero at a smooth local maximum or minimum. - Read both \(f(0)\) and \(f'(0)\) from the graphs. - Use the point and slope to write the tangent line.

Solution

1. The green graph represents \(f\), and the orange graph represents \(f'\). 2. At the maxima and minimum of the green graph, the orange graph crosses the x-axis. This matches the fact that \(f'(x)=0\) at critical points of \(f\). 3. At \(x=0\), the green graph gives \(f(0)=0\), and the orange graph gives \(f'(0)=2\). Thus, the tangent line passes through \((0,0)\) with slope \(2\). 4. The tangent line is \(y=2x\).

Answer

a) The green graph is \(f\), and the orange graph is \(f'\). The zeros of the orange graph occur at the extrema of the green graph. b) \(y=2x\)
53389912
The graph of \(f(x)=1.25^x\) is shown. Describe the tangent-slope function, or the graph of \(f^{\prime}\). Use the behavior of \(f\) to explain whether \(f^{\prime}\) has any zeros.
Figure for problem 533899

Hints

- Determine the sign of every tangent slope on the graph of \(f\). - Check whether the graph ever has a horizontal tangent line. - Observe how the steepness changes from left to right.

Solution

1. The exponential function \(f(x)=1.25^x\) is positive and strictly increasing for every real \(x\). Therefore, \(f^{\prime}(x)>0\) for all \(x\), so the derivative has no zeros. 2. The graph of \(f\) becomes steeper from left to right. Therefore, \(f^{\prime}\) is also strictly increasing. 3. As \(x\to-\infty\), the graph of \(f\) becomes nearly horizontal, so \(f^{\prime}(x)\to0\) from above. The derivative graph is qualitatively another increasing exponential curve above the x-axis.

Answer

The graph of \(f^{\prime}\) is an increasing exponential curve entirely above the x-axis. It approaches \(0\) from above as \(x\to-\infty\) and has no zeros.
53390112
The graph of \(f(x)=\frac{3}{x}\) is shown. Determine the sign of the tangent-slope function \(f^{\prime}\) on each interval \(x<0\) and \(x>0\). Justify your answer using the graph.
Figure for problem 533901

Hints

- Determine whether each branch is increasing or decreasing. - A decreasing function has negative tangent slopes. - Remember that \(x=0\) is not in the domain.

Solution

1. For \(x<0\), the left branch of \(f\) is strictly decreasing. Therefore, every tangent slope is negative and \(f^{\prime}(x)<0\). 2. For \(x>0\), the right branch is also strictly decreasing. Therefore, every tangent slope is negative and \(f^{\prime}(x)<0\). 3. Thus, the derivative graph lies below the x-axis at every input in the domain, \(x\ne0\).

Answer

For both \(x<0\) and \(x>0\), \(f^{\prime}(x)<0\).
53392712
The graph of \(f\) is shown. Use the graph to find the x-coordinates of the zeros of \(f^{\prime}\). Briefly justify your answer by examining the slope of \(f\).
Figure for problem 533927

Hints

- The derivative describes the tangent slope of the original function. - Look for local maxima and minima. - A smooth local extremum has a horizontal tangent line.

Solution

1. Zeros of \(f^{\prime}\) occur where the graph of \(f\) has horizontal tangent lines. 2. The graph has a local maximum at \(x=-2\) and a local minimum at \(x=2\). 3. Therefore, \(f^{\prime}(-2)=0\) and \(f^{\prime}(2)=0\).

Answer

The zeros of \(f^{\prime}\) are \(x=-2\) and \(x=2\).
53417412
The graph of a quadratic function \(g\) is shown with tangent lines at \(x=0\) and \(x=4\). Point \(S\) marks the vertex. a) Use the tangent lines to find \(g^{\prime}(0)\) and \(g^{\prime}(4)\). b) At what input is \(g^{\prime}(x)=0\)? Give the correct mathematical name for point \(S\). c) Compare the slopes at \(x=1\) and \(x=3\). Which is greater?
Figure for problem 534174

Hints

- Calculate each line slope as change in \(y\) divided by change in \(x\). - The tangent line at the vertex of a smooth parabola is horizontal. - Compare a negative slope with a positive slope.

Solution

1. The tangent line at \(x=0\) passes through \((0,-1)\) and \((1,-2)\). Its slope is \(\frac{-2-(-1)}{1-0}=-1\), so \(g^{\prime}(0)=-1\). 2. The tangent line at \(x=4\) passes through \((4,-1)\) and \((5,0)\). Its slope is \(\frac{0-(-1)}{5-4}=1\), so \(g^{\prime}(4)=1\). 3. At the vertex \(S(2,-2)\), the tangent line is horizontal. Thus, \(g^{\prime}(2)=0\). Point \(S\) is the vertex and a local minimum. 4. At \(x=1\), the graph is decreasing, so the slope is negative. At \(x=3\), it is increasing, so the slope is positive. Therefore, \(g^{\prime}(3)>g^{\prime}(1)\).

Answer

a) \(g^{\prime}(0)=-1\) and \(g^{\prime}(4)=1\) b) \(g^{\prime}(2)=0\); \(S\) is the vertex and a local minimum. c) The slope at \(x=3\) is greater.
53419912
Graph A shows a function \(f\). Decide whether graph 1 or graph 2 represents \(f^{\prime}\). Justify your choice using features such as zeros and local extrema.
Figure for problem 534199

Hints

- Determine where the original function is increasing and decreasing. - The derivative is zero where the original graph has a horizontal tangent line. - Check the sign of each candidate on both sides of the zero.

Solution

1. The graph of \(f\) is an upward-opening parabola with a local minimum at \(x=0\). 2. Therefore, \(f^{\prime}(0)=0\). Both candidate graphs have a zero at \(x=0\). 3. For \(x<0\), the graph of \(f\) is decreasing, so \(f^{\prime}(x)<0\). For \(x>0\), it is increasing, so \(f^{\prime}(x)>0\). 4. Graph 1 has this sign pattern, while graph 2 has the opposite sign pattern. Therefore, graph 1 represents \(f^{\prime}\).

Answer

Graph 1 represents \(f^{\prime}\).
53421212
The graph of \(f\) is shown. Estimate the slope at \(x=0\). Then describe the graph of \(f^{\prime}\) and the relationship between the vertex of \(f\) and the graph of \(f^{\prime}\).
Figure for problem 534212

Hints

- The tangent line at the highest point of a smooth parabola is horizontal. - Use symmetry to compare slopes at opposite inputs. - The derivative of a quadratic function is linear.

Solution

1. At \(x=0\), the graph has its maximum and the tangent line is horizontal. Therefore, \(f^{\prime}(0)=0\). 2. Because \(f\) is a downward-opening parabola, its tangent slopes decrease steadily as \(x\) increases. By symmetry, the slopes are positive to the left of the vertex and negative to the right. 3. Therefore, the graph of \(f^{\prime}\) is a decreasing line through \((0,0)\). Its vertical scale can be estimated from the slopes of \(f\). 4. The x-coordinate of the vertex of \(f\) is the zero of \(f^{\prime}\).

Answer

The slope at \(x=0\) is \(0\). The derivative graph is a decreasing line through \((0,0)\). The vertex of \(f\) occurs at the same input as the zero of \(f^{\prime}\).
53421712
The graph of a quadratic function \(f\) is shown with tangent lines \(t_1\), \(t_2\), and \(t_3\) at \(x_1=-2\), \(x_2=0\), and \(x_3=2\). a) Read the slopes \(m_1\), \(m_2\), and \(m_3\) from the tangent lines. b) A point \(Q(x,y)\) on the derivative graph has the tangent slope of \(f\) at \(x\) as its y-coordinate. Give the coordinates of \(Q_1\), \(Q_2\), and \(Q_3\). c) What type of function do you expect \(f^{\prime}\) to be: constant, linear, quadratic, or another type? Justify your answer.
Figure for problem 534217

Hints

- Use rise over run to find each tangent-line slope. - The y-coordinate on the derivative graph equals the tangent slope at that input. - Plot the three derivative points mentally and identify their pattern. - Recall the degree of the derivative of a quadratic polynomial.

Solution

1. At \(x=-2\), tangent line \(t_1\) falls \(2\) units for each unit to the right, so \(m_1=-2\). At \(x=0\), tangent line \(t_2\) is horizontal, so \(m_2=0\). At \(x=2\), tangent line \(t_3\) rises \(2\) units for each unit to the right, so \(m_3=2\). 2. The corresponding derivative points are \(Q_1(-2,-2)\), \(Q_2(0,0)\), and \(Q_3(2,2)\). 3. These three points lie on a line through the origin. Also, the derivative of a quadratic function is linear. Therefore, \(f^{\prime}\) is a linear function.

Answer

a) \(m_1=-2\), \(m_2=0\), and \(m_3=2\) b) \(Q_1(-2,-2)\), \(Q_2(0,0)\), and \(Q_3(2,2)\) c) \(f^{\prime}\) is linear.
53423312
The graph of a parabola \(f\) and its tangent line \(t\) at \(A(2,0)\) are shown. 1. Use convenient grid points to find the equation of \(t\). 2. Find the angle of inclination \(\alpha\) of \(t\).
Figure for problem 534233

Hints

- Choose two exact grid points on the tangent line. - Use the slope formula. - The slope and angle of inclination satisfy \(m=\tan(\alpha)\). - Measure the angle from the positive x-axis.

Solution

1. The tangent passes through \(A(2,0)\) and \((3,2)\), so its slope is \(m=\frac{2-0}{3-2}=2\). 2. Using \(A\), \(0=2(2)+b\), so \(b=-4\). Therefore, \(t\) is \(y=2x-4\). 3. Since \(\tan(\alpha)=2\), \(\alpha=\arctan(2)\approx63.43^\circ\).

Answer

1. \(t: y=2x-4\) 2. \(\alpha\approx63.43^\circ\)
53423512
The graph of a rational function \(f\) and its tangent line \(t\) at \(P(1,0)\) are shown. 1. Find the equation of \(t\). 2. Find its angle of inclination \(\alpha\).
Figure for problem 534235

Hints

- Choose two exact points on the orange line. - Relate slope to the angle of inclination. - A line with negative slope has an inclination angle between \(90^\circ\) and \(180^\circ\).

Solution

1. The tangent passes through \(P(1,0)\) and \((3,-1)\), so \(m=\frac{-1-0}{3-1}=-0.5\). 2. Using \(P\), \(0=-0.5(1)+b\), so \(b=0.5\). Therefore, \(t\) is \(y=-0.5x+0.5\). 3. Since \(\arctan(-0.5)\approx-26.57^\circ\), add \(180^\circ\) to obtain the angle of inclination: \(\alpha\approx153.43^\circ\).

Answer

1. \(t: y=-0.5x+0.5\) 2. \(\alpha\approx153.43^\circ\)
53423712
The graph of \(f\) and its tangent line \(t\) at the inflection point \(W(0,0)\) are shown. 1. Find the equation of \(t\). 2. Find its angle of inclination \(\alpha\).
Figure for problem 534237

Hints

- Use the origin as one of the two points for calculating the slope. - Read the horizontal and vertical changes to another grid point. - A negative slope corresponds to an inclination angle between \(90^\circ\) and \(180^\circ\).

Solution

1. The tangent passes through \(W(0,0)\) and the marked point \((2,-1.5)\), so its slope is \(m=\frac{-1.5-0}{2-0}=-0.75\). 2. Because the line passes through the origin, its equation is \(y=-0.75x\). 3. Since \(\arctan(-0.75)\approx-36.87^\circ\), its angle of inclination is \(\alpha\approx143.13^\circ\).

Answer

1. \(t: y=-0.75x\) 2. \(\alpha\approx143.13^\circ\)
53429412
The graph of \(f\) has marked points \(A\), \(B\), and \(C\). For each point, determine whether \(f(x)\), \(f^{\prime}(x)\), and \(f^{\prime\prime}(x)\) are positive, negative, or zero. Complete the table with \(+\), \(-\), or \(0\). <table> <tr><th>Point</th><th>\(f(x)\)</th><th>\(f^{\prime}(x)\)</th><th>\(f^{\prime\prime}(x)\)</th></tr> <tr><td>\(A\)</td><td>...</td><td>...</td><td>...</td></tr> <tr><td>\(B\)</td><td>...</td><td>...</td><td>...</td></tr> <tr><td>\(C\)</td><td>...</td><td>...</td><td>...</td></tr> </table>
Figure for problem 534294

Hints

- Use vertical position to determine the sign of the function value. - Use increasing, decreasing, or horizontal behavior to determine the sign of the first derivative. - Use concavity to determine the sign of the second derivative. - Examine the tangent line at each marked point.

Solution

1. At \(A(1,0)\), the point lies on the x-axis, so \(f(1)=0\). The graph is decreasing, so \(f^{\prime}(1)<0\). The graph is concave up, so \(f^{\prime\prime}(1)>0\). 2. At \(B(2,-0.5)\), the point lies below the x-axis, so \(f(2)<0\). The tangent line is horizontal at the vertex, so \(f^{\prime}(2)=0\). The graph is concave up, so \(f^{\prime\prime}(2)>0\). 3. At \(C(3,0)\), the point lies on the x-axis, so \(f(3)=0\). The graph is increasing, so \(f^{\prime}(3)>0\). The graph is concave up, so \(f^{\prime\prime}(3)>0\).

Answer

The completed table is: <table> <tr><th>Point</th><th>\(f(x)\)</th><th>\(f^{\prime}(x)\)</th><th>\(f^{\prime\prime}(x)\)</th></tr> <tr><td>\(A\)</td><td>\(0\)</td><td>\(-\)</td><td>\(+\)</td></tr> <tr><td>\(B\)</td><td>\(-\)</td><td>\(0\)</td><td>\(+\)</td></tr> <tr><td>\(C\)</td><td>\(0\)</td><td>\(+\)</td><td>\(+\)</td></tr> </table>
53429512
The graph of \(f\) has marked points \(A\), \(B\), and \(C\). Match each description to the appropriate point, and justify your choices using the signs of \(f'(x)\) and \(f''(x)\). a) The graph is increasing and concave down. b) The graph has a horizontal tangent line. c) The graph is decreasing and concave down.
Figure for problem 534295

Hints

- An increasing graph has a positive first derivative. - A decreasing graph has a negative first derivative. - Concave down means the second derivative is negative. - Locate the point with a horizontal tangent line.

Solution

1. At point \(A\), the graph is increasing, so \(f^{\prime}(x)>0\), and it is concave down, so \(f^{\prime\prime}(x)<0\). Thus, \(A\) matches the first description. 2. Point \(B\) is the local maximum. The tangent line is horizontal, so \(f^{\prime}(x)=0\). Thus, \(B\) matches the second description. 3. At point \(C\), the graph is decreasing, so \(f^{\prime}(x)<0\), and it remains concave down, so \(f^{\prime\prime}(x)<0\). Thus, \(C\) matches the third description.

Answer

a) \(A\) b) \(B\) c) \(C\)
53430412
The graph of a periodic function \(f\) has marked points \(A\) and \(B\). At each point, determine the sign of \(f^{\prime}(x)\) and the sign of \(f^{\prime\prime}(x)\).
Figure for problem 534304

Hints

- Use increasing or decreasing behavior to determine the sign of the first derivative. - Use concavity to determine the sign of the second derivative.

Solution

1. At point \(A\), the graph is increasing, so \(f^{\prime}(x)>0\). The graph is concave down, so \(f^{\prime\prime}(x)<0\). 2. At point \(B\), the graph is decreasing, so \(f^{\prime}(x)<0\). The graph is concave up, so \(f^{\prime\prime}(x)>0\).

Answer

Point \(A\): \(f^{\prime}(x)>0\) and \(f^{\prime\prime}(x)<0\) Point \(B\): \(f^{\prime}(x)<0\) and \(f^{\prime\prime}(x)>0\)
53450612
The graph of \(h\) has a horizontal inflection point at \(x=1\). Describe the graph of \(h^{\prime}\), and briefly explain its behavior near \(x=1\).
Figure for problem 534506

Hints

- Determine the tangent slope at a horizontal inflection point. - Check whether the original function increases or decreases on each side. - A zero without a sign change appears as a touch rather than a crossing.

Solution

1. At a horizontal inflection point, the tangent line is horizontal, so \(h^{\prime}(1)=0\). 2. The function \(h\) is increasing on both sides of \(x=1\). Therefore, \(h^{\prime}(x)>0\) for \(x\ne1\). 3. The derivative graph touches the x-axis at \(x=1\) without crossing it. Because the original graph has point symmetry about \((1,1)\), the derivative graph is symmetric about the vertical line \(x=1\). 4. Thus, the derivative graph is a smooth curve symmetric about \(x=1\), with a minimum at \((1,0)\) and values above the x-axis elsewhere.

Answer

The derivative graph is symmetric about \(x=1\), touches the x-axis at \((1,0)\), and remains positive on both sides, so the zero has no sign change.
53450912
The graph of \(f\) approaches the horizontal asymptote \(y=1\) as \(x\to\infty\). Describe the behavior of \(f^{\prime}\) for \(x>0\). What value does \(f^{\prime}(x)\) approach for very large \(x\)? Justify your answer.
Figure for problem 534509

Hints

- A graph approaching a horizontal line becomes nearly flat. - Determine whether the original function is increasing or decreasing. - Nearly horizontal tangent lines have slopes near zero.

Solution

1. The graph of \(f\) is strictly increasing for \(x>0\), so \(f^{\prime}(x)>0\) throughout that interval. 2. As the graph approaches the horizontal asymptote, it becomes flatter and its tangent slopes decrease. 3. Therefore, \(f^{\prime}(x)\to0\) as \(x\to\infty\). The derivative graph stays above the x-axis and approaches it from above.

Answer

For \(x>0\), \(f^{\prime}(x)>0\), and \(f^{\prime}(x)\to0\) as \(x\to\infty\).
53452812
The graph of a rational function \(f\) is shown. Determine the number of zeros of \(f^{\prime}\) and the number of zeros of \(f^{\prime\prime}\). Briefly justify your answer.
Figure for problem 534528

Hints

- Zeros of the first derivative occur at horizontal tangent lines. - Zeros of the second derivative can occur at inflection points. - Analyze each continuous branch separately.

Solution

1. On each interval of its domain, the graph is strictly decreasing and has no horizontal tangent lines. Therefore, \(f^{\prime}\) has \(0\) zeros. 2. Each branch keeps the same concavity and has no inflection point. The change across the vertical asymptote does not count because the function is undefined there. Therefore, \(f^{\prime\prime}\) has \(0\) zeros.

Answer

\(f^{\prime}\) has \(0\) zeros, and \(f^{\prime\prime}\) has \(0\) zeros.
53458112
The graph shows \(f(x)=\sqrt{x}\) and its derivative \(f^{\prime}\). a) Use the graph to find the slope of the tangent line to \(f\) at \(x=1\) and at \(x=4\). b) At what x-value do \(f(x)\) and \(f^{\prime}(x)\) have the same value?
Figure for problem 534581

Hints

- The derivative graph gives the tangent slope of the original function. - Read the derivative value at each specified x-value. - The two functions have the same value where their graphs intersect.

Solution

1. The slope of the tangent line at \(x\) equals \(f^{\prime}(x)\). 2. From the derivative graph, \(f^{\prime}(1)=0.5\) and \(f^{\prime}(4)=0.25\). 3. The function and derivative have the same value at an intersection of their graphs. The intersection occurs at \(x=0.5\). 4. Algebraically, \(\sqrt{0.5}=\frac{1}{2\sqrt{0.5}}\approx0.707\), confirming the intersection.

Answer

a) At \(x=1\), the slope is \(0.5\); at \(x=4\), the slope is \(0.25\). b) \(x=0.5\)
53498112
The graph of \(f\) and its tangent line at \(P(0,2)\) are shown. Find the slope of the tangent line and therefore the value of \(f'(0)\).
Figure for problem 534981

Hints

- Choose two points on the tangent line. - The tangent slope equals the derivative value at the point of tangency. - Use vertical change divided by horizontal change.

Solution

1. The derivative value \(f'(0)\) equals the slope of the tangent line at \(P\). 2. The tangent passes through \(P(0,2)\) and the grid point \((4,3)\). 3. Its slope is \(m=\frac{3-2}{4-0}=\frac{1}{4}=0.25\). 4. Therefore, \(f'(0)=0.25\).

Answer

The tangent slope is \(0.25\), so \(f'(0)=0.25\).
53501812
The graph of \(f\) is shown. a) Determine the \(x\)-values where \(f^{\prime}(x)=0\). Briefly justify your answer using the graph of \(f\). b) Is \(f^{\prime}(0)\) positive, negative, or zero? Explain how the graph shows this.
Figure for problem 535018

Hints

- Identify the local maximum and local minimum. - What is the slope of the tangent line at a local extremum? - Determine whether the graph is increasing or decreasing at \(x=0\).

Solution

1. The graph has a local maximum at \(x=-2\) and a local minimum at \(x=2\). 2. The tangent line is horizontal at each local extremum, so \(f^{\prime}(-2)=0\) and \(f^{\prime}(2)=0\). 3. Near \(x=0\), the graph is decreasing. Therefore, its tangent slope is negative and \(f^{\prime}(0)<0\).

Answer

a) \(f^{\prime}(x)=0\) at \(x=-2\) and \(x=2\), where the graph has horizontal tangent lines. b) \(f^{\prime}(0)\) is negative because the graph is decreasing at \(x=0\).
52988912
For an exponential function \(f(x)=b^x\), where \(b>0\), the slope at \(x=0\) can be approximated by \(\frac{f(h)-f(0)}{h}=\frac{b^h-1}{h}\) for a small positive value of \(h\). a) Use \(h=0.0001\) to approximate \(f'(0)\) for \(b=2\) and \(b=4\). b) A special base has slope \(1\) at \(x=0\). Solve \(\frac{b^h-1}{h}=1\) for \(b\), and use \(h=0.0001\) to approximate this base.

Hints

- Substitute each base into the given difference quotient. - Keep enough calculator precision before rounding. - Isolate \(b^h\) before taking the \(h\)th root. - Rewrite an \(h\)th root as a power of \(1/h\).

Solution

1. For \(b=2\), \(\frac{2^{0.0001}-1}{0.0001}\approx 0.6932\). For \(b=4\), \(\frac{4^{0.0001}-1}{0.0001}\approx 1.3864\). 2. Solve the equation algebraically: \(\frac{b^h-1}{h}=1\) implies \(b^h=1+h\). Therefore, \(b=(1+h)^{1/h}\). With \(h=0.0001\), \(b=(1.0001)^{10000}\approx 2.7181\).

Answer

a) For \(b=2\), \(f'(0)\approx 0.6932\). For \(b=4\), \(f'(0)\approx 1.3864\). b) \(b\approx 2.7181\)
53217112
The left coordinate plane shows the graph of a function \(f\). The right coordinate plane shows three possible derivative graphs: \(A\) in blue, \(B\) in red, and \(C\) in green. Which graph represents \(f'\)? Justify your choice using the behavior of \(f\).
Figure for problem 532171

Hints

- Locate the local maximum and minimum of \(f\). - What is the derivative value at a smooth extremum? - Determine where \(f\) is increasing and decreasing. - Match those intervals to the sign of each candidate graph.

Solution

1. The graph of \(f\) has a local maximum at \(x=-1\) and a local minimum at \(x=1\). Therefore, \(f'(-1)=0\) and \(f'(1)=0\). This eliminates graph \(C\), which has only one zero. 2. The function increases for \(x<-1\) and \(x>1\), so \(f'(x)>0\) there. It decreases for \(-1<x<1\), so \(f'(x)<0\) there. 3. Only graph \(A\) has zeros at \(-1\) and \(1\), is negative between them, and is positive outside them. Therefore, graph \(A\) represents \(f'\).

Answer

Graph \(A\) represents \(f'\).
53235612
The graph of \(f\) is shown. Decide whether each statement about \(f'\) is true or false. Justify your decisions. 1) The graph of \(f'\) lies entirely below the x-axis on \([-1,1]\). 2) \(f'(-2)=0\). 3) The graph of \(f'\) has a local maximum at \(x=0\). 4) \(f'(3)<0\).
Figure for problem 532356

Hints

- Identify where \(f\) is increasing and decreasing. - Relate the sign of \(f'\) to the direction of change of \(f\). - At a smooth extremum, the tangent slope is zero. - Where does \(f\) have its most negative slope?

Solution

1. Statement 1 is true. The function \(f\) is decreasing throughout \([-1,1]\), so \(f'(x)<0\) there. 2. Statement 2 is true. The graph of \(f\) has a local maximum at \(x=-2\), so its tangent is horizontal and \(f'(-2)=0\). 3. Statement 3 is false. At \(x=0\), the graph of \(f\) has its steepest negative slope. Therefore, \(f'\) has a local minimum there, not a local maximum. 4. Statement 4 is false. To the right of the local minimum at \(x=2\), the graph of \(f\) is increasing, so \(f'(3)>0\).

Answer

1) True 2) True 3) False 4) False
53235912
The graph of \(f\) and the tangent line \(t\) at the inflection point \(W(0,0)\) are shown. a) Find all inputs where \(f'(x)=0\). b) Use the slope of \(t\) to find \(f'(0)\). c) Give the largest interval on which \(f\) is strictly decreasing.
Figure for problem 532359

Hints

- The derivative gives the tangent slope at each input. - At a smooth local maximum or minimum, the tangent is horizontal. - Use a slope triangle on the red tangent line. - Identify the interval where the graph moves downward from left to right.

Solution

1. The graph has a local maximum at \(x=-2\) and a local minimum at \(x=2\). The tangents are horizontal there, so \(f'(-2)=0\) and \(f'(2)=0\). 2. The tangent \(t\) passes through \((0,0)\) and \((1,-3)\). Its slope is \(\frac{-3-0}{1-0}=-3\), so \(f'(0)=-3\). 3. The graph decreases from the local maximum to the local minimum. Thus, the largest interval is \([-2,2]\).

Answer

a) \(x=-2\) and \(x=2\) b) \(f'(0)=-3\) c) \([-2,2]\)
53241912
The graphs of \(f\) and \(g\) are shown. The graph of \(g\) is a translation of the graph of \(f\). The tangent line \(t\) to the graph of \(f\) at \(x=2\) is also shown. a) Use the marked vertices \(S_f\) and \(S_g\) to describe the horizontal and vertical translation. Write \(g\) in the form \(g(x)=f(x-d)+c\). b) Find the slope of \(t\) and therefore the value of \(f'(2)\). c) What is the slope of the graph of \(g\) at \(x=5\)? Justify your answer geometrically, and find the equation of the tangent line to \(g\) at that input.
Figure for problem 532419

Hints

- Compare the coordinates of the two vertices. - Use two readable points on \(t\) to calculate its slope. - A translation does not change the slope at corresponding points. - Use the translated point and the slope in point-slope form.

Solution

1. The vertices are \(S_f(1,0.5)\) and \(S_g(4,2.5)\). Therefore, the graph is translated \(3\) units right and \(2\) units up, so \(g(x)=f(x-3)+2\). 2. The line \(t\) passes through \((1,0)\) and \(P(2,1)\), so its slope is \(\frac{1-0}{2-1}=1\). Therefore, \(f'(2)=1\). 3. A translation preserves slopes at corresponding points. Since the graph moved \(3\) units right, \(x=5\) on \(g\) corresponds to \(x=2\) on \(f\). Thus, \(g'(5)=f'(2)=1\). 4. The translated point is \((5,3)\). A line of slope \(1\) through that point is \(y-3=x-5\), or \(y=x-2\).

Answer

a) The graph is translated \(3\) units right and \(2\) units up, so \(g(x)=f(x-3)+2\). b) The slope is \(1\), so \(f'(2)=1\). c) The slope is \(1\), and the tangent line is \(y=x-2\).
53252412
Panel 1 shows a cubic function \(f\) and its tangent line \(t\) at \(P(2,2)\). Panel 2 shows three candidate derivative graphs, \(g_1\), \(g_2\), and \(g_3\). a) Find the slope of \(t\) from the graph. What is \(f'(2)\)? b) Use this value and the extrema and monotonicity of \(f\) to identify which candidate is \(f'\).
Figure for problem 532524

Hints

- The derivative value equals the tangent slope. - Use two points on \(t\) to calculate its slope. - The derivative is zero at smooth local extrema. - Match the sign of each candidate to the increasing and decreasing intervals of \(f\).

Solution

1. The tangent passes through \(P(2,2)\) and \((4,0)\). Its slope is \(\frac{0-2}{4-2}=-1\), so \(f'(2)=-1\). 2. All three candidates have value \(-1\) at \(x=2\), so that value alone does not determine the answer. 3. The graph of \(f\) has a local maximum near \(x=0.85\) and a local minimum near \(x=3.15\). Therefore, \(f'\) must have zeros near those inputs. 4. Only \(g_1\) has zeros near \(0.85\) and \(3.15\). It is also positive where \(f\) increases and negative where \(f\) decreases. Thus, \(g_1\) represents \(f'\).

Answer

a) The slope is \(-1\), so \(f'(2)=-1\). b) \(g_1\) represents \(f'\).
53252912
The graph of a cubic polynomial \(f\) is shown. Decide whether each statement about \(f\) and \(f'\) is true or false. 1) The graph of \(f'\) has exactly two zeros. 2) On \([-2,2]\), the graph of \(f'\) lies above the x-axis. 3) The graph of \(f\) has an inflection point at \((0,1)\). 4) As \(x\to-\infty\), \(f'(x)\to-\infty\).
Figure for problem 532529

Hints

- Zeros of the derivative occur at smooth extrema of the original function. - Use increasing and decreasing behavior to determine the derivative's sign. - Look for where the graph changes concavity. - Consider the slope of the graph far to the left.

Solution

1. Statement 1 is true. The graph of \(f\) has a local maximum at \(x=-2\) and a local minimum at \(x=2\), so \(f'\) has zeros at both inputs. 2. Statement 2 is false. The graph of \(f\) decreases between the extrema, so \(f'(x)<0\) for \(-2<x<2\), with zeros at the endpoints. 3. Statement 3 is true. The change in concavity occurs midway between the symmetric extrema, at \(x=0\), and the graph gives \(f(0)=1\). 4. Statement 4 is false. Far to the left, the graph is increasing ever more steeply, so \(f'(x)\to+\infty\) as \(x\to-\infty\).

Answer

1) True 2) False 3) True 4) False
53253012
The graph of \(f\) is shown. Which expression represents \(f'\)? Justify your answer. A: \(f'(x)=0.5x^2-x-1.5\) B: \(f'(x)=-0.5x^2+x+1.5\) C: \(f'(x)=x^2-2x-3\) D: \(f'(x)=0.5x^2+x-1.5\)
Figure for problem 532530

Hints

- Find the x-coordinates of the local maximum and minimum. - The derivative must be zero at those inputs. - Use the increasing and decreasing intervals to determine the derivative's sign pattern. - Estimate one slope to distinguish candidates with the same zeros.

Solution

1. The graph of \(f\) has a local maximum at \(x=-1\) and a local minimum at \(x=3\). Therefore, \(f'\) must have zeros at \(-1\) and \(3\). This eliminates option D. 2. The function increases for \(x<-1\) and \(x>3\), so \(f'\) must be positive there. It decreases between the extrema, so \(f'\) must be negative there. Thus, its graph opens upward, eliminating option B. 3. Options A and C have the correct zeros and sign pattern. Estimate the slope of \(f\) near the inflection point \(x=1\). The graph suggests a slope near \(-2\). 4. Option A gives \(f'(1)=0.5-1-1.5=-2\), while option C gives \(f'(1)=1-2-3=-4\). Therefore, option A matches the graph.

Answer

A: \(f'(x)=0.5x^2-x-1.5\)
53253112
The graph of \(f\) is shown. Decide which statements about \(f'\) are true. Give a detailed justification for each decision. 1) The graph of \(f'\) lies above the x-axis on \((0,4)\). 2) \(f'(2)=0\). 3) \(f'(1)=f'(3)\). 4) \(f'(0)=-2\).
Figure for problem 532531

Hints

- The derivative is the graph's tangent slope. - Relate increasing and decreasing behavior to the sign of the derivative. - At a smooth extremum, the derivative is zero. - Do not confuse a function value with a derivative value. - Use symmetry about the inflection point.

Solution

1. Statement 1 is true. The graph of \(f\) increases throughout \((0,4)\) and has no horizontal tangent there, so \(f'(x)>0\) on that interval. 2. Statement 2 is false. At \(x=2\), the graph has an inflection point with positive slope; the slope is approximately \(3\), not \(0\). 3. Statement 3 is true. The graph is point-symmetric about its inflection point \((2,2)\), so the tangent slopes at inputs equally spaced from \(2\), such as \(1\) and \(3\), are equal. 4. Statement 4 is false. At \(x=0\), the graph has a local minimum, so \(f'(0)=0\). The value \(-2\) is \(f(0)\), not the derivative value.

Answer

1) True 2) False 3) True 4) False
53259112
The graph of a function \(f\) and the tangent line \(t\) at \(x=0\) are shown. Within the displayed interval \([-5,5]\), answer the following questions about the derivative \(f^{\prime}\). a) Find the zeros of \(f^{\prime}\). Briefly justify your answer. b) Use tangent line \(t\) to find \(f^{\prime}(0)\). c) State the intervals on which \(f^{\prime}(x)>0\). Justify your answer using the behavior of \(f\).
Figure for problem 532591

Hints

- The derivative gives the slope of the tangent line to the graph of \(f\). - Look for points where the graph has a horizontal tangent. - Use two points on tangent line \(t\) to calculate its slope. - Determine where the graph of \(f\) is increasing.

Solution

1. The zeros of \(f^{\prime}\) occur where the graph of \(f\) has horizontal tangent lines. The graph has a local maximum at \(x=-2\) and a local minimum at \(x=2\), so the zeros are \(x=-2\) and \(x=2\). 2. The tangent line passes through \((0,0)\) and \((1,-3)\). Its slope is \(\frac{-3-0}{1-0}=-3\), so \(f^{\prime}(0)=-3\). 3. The graph of \(f\) is increasing from \(x=-5\) to \(x=-2\) and from \(x=2\) to \(x=5\). Therefore, \(f^{\prime}(x)>0\) on \([-5,-2)\) and \((2,5]\).

Answer

a) \(x=-2\) and \(x=2\) b) \(f^{\prime}(0)=-3\) c) \([-5,-2)\) and \((2,5]\)
53262712
The graph of a function \(f\) is shown. Decide whether each statement is true or false. (1) The derivative \(f^{\prime}\) has exactly three zeros on \([-3,3]\). (2) For \(x>2\), \(f^{\prime}(x)>0\). (3) The second derivative \(f^{\prime\prime}\) has exactly two zeros on \([-3,3]\). (4) The graph of \(f^{\prime}\) is symmetric about the y-axis. (5) \(f^{\prime}(1)>0\).
Figure for problem 532627

Hints

- Zeros of the first derivative occur where the graph has horizontal tangent lines. - The sign of the first derivative indicates whether the function is increasing or decreasing. - Zeros of the second derivative can occur where the graph changes concavity. - Recall how the derivative of an even function behaves.

Solution

1. Statement (1) is true. The graph of \(f\) has horizontal tangent lines at its local maxima \(x=-2\) and \(x=2\) and at its local minimum \(x=0\). Thus, \(f^{\prime}\) has exactly three zeros. 2. Statement (2) is false. The function is decreasing for \(x>2\), so \(f^{\prime}(x)<0\) there. 3. Statement (3) is true. The graph changes concavity twice, near \(x=-1.15\) and \(x=1.15\), so \(f^{\prime\prime}\) has exactly two zeros on the interval. 4. Statement (4) is false. The graph of \(f\) is symmetric about the y-axis, so \(f\) is even and \(f^{\prime}\) is odd. Therefore, the graph of \(f^{\prime}\) is symmetric about the origin. 5. Statement (5) is true. The graph of \(f\) is increasing at \(x=1\), so \(f^{\prime}(1)>0\).

Answer

(1) True (2) False (3) True (4) False (5) True
53267812
The graph of the cubic function \(f(x)=0.25x^3-3x\) and its tangent line at the inflection point are shown. a) Use the graph to find the coordinates of the two local extrema. What is true about \(f^{\prime}\) at these points? b) Use the tangent line at \(W(0,0)\) to find \(f^{\prime}(0)\). c) On which interval is the graph concave down, and on which interval is it concave up? State the sign of \(f^{\prime\prime}\) on each interval.
Figure for problem 532678

Hints

- At a smooth local maximum or minimum, the tangent line is horizontal. - Use a rise-over-run calculation on the tangent line at the origin. - Concavity describes whether tangent slopes are decreasing or increasing. - Relate concavity to the sign of the second derivative.

Solution

1. The graph has a local maximum at \((-2,4)\) and a local minimum at \((2,-4)\). The tangent line is horizontal at each point, so \(f^{\prime}(-2)=0\) and \(f^{\prime}(2)=0\). 2. The tangent line at the origin falls \(3\) units for every increase of \(1\) unit in \(x\). Its slope is \(-3\), so \(f^{\prime}(0)=-3\). 3. For \(x<0\), the graph is concave down, so \(f^{\prime\prime}(x)<0\). For \(x>0\), the graph is concave up, so \(f^{\prime\prime}(x)>0\).

Answer

a) Local maximum: \((-2,4)\); local minimum: \((2,-4)\). At both inputs, \(f^{\prime}(x)=0\). b) \(f^{\prime}(0)=-3\) c) Concave down with \(f^{\prime\prime}(x)<0\) for \(x<0\); concave up with \(f^{\prime\prime}(x)>0\) for \(x>0\).
53316312
The figure shows the graph of \(f\) in black and three candidate graphs: \(g\) in red, \(h\) in blue, and \(k\) in green. One candidate represents \(f^{\prime}\). Which graph is the derivative? Justify your choice by comparing the behavior of \(f\) with the values of the candidate functions.
Figure for problem 533163

Hints

- Locate the horizontal tangent lines on the graph of \(f\). - The derivative must be zero at those inputs. - Determine where \(f\) is increasing and decreasing, then match the derivative sign. - A cubic polynomial has a quadratic derivative.

Solution

1. The graph of \(f\) has a local maximum near \(x=-0.15\) and a local minimum near \(x=2.15\). Therefore, \(f^{\prime}\) must have zeros near those inputs. Both \(g\) and \(h\) have the required zeros. 2. Between the two extrema, \(f\) is decreasing. Therefore, \(f^{\prime}\) must be negative on that interval. 3. Graph \(g\) lies below the x-axis between the two zeros, while graph \(h\) lies above it. Thus, \(g\) has the correct sign pattern. 4. Graph \(k\) has only one zero and is linear, so it cannot be the derivative of the displayed cubic function. Therefore, graph \(g\) represents \(f^{\prime}\).

Answer

The red graph \(g\) represents \(f^{\prime}\).
53369212
Figure 1 shows the graph of a function \(g\), and Figure 2 shows the graph of its derivative \(g'\). Use the graphs to determine: a) \(g(2)\), b) the slope of \(g\) at \(x = 2\), c) \(g'(1)\), d) one value of \(x\) for which \(g(x) = 1\), e) all \(x\)-values where \(g\) has a horizontal tangent, f) one \(x\)-value where the slope of \(g\) is \(3\).
Figure for problem 533692

Hints

- Read function values from the graph of \(g\) and slopes from the graph of \(g'\). - Horizontal tangents occur where the derivative is zero. - A requested slope is a requested value of the derivative.

Solution

1. From Figure 1, \(g(2) = -3\). 2. The slope at \(x = 2\) is \(g'(2) = 0\). 3. From Figure 2, \(g'(1) = -3\). 4. Figure 1 shows \(g(0) = 1\), so \(x = 0\) is one solution. 5. Horizontal tangents occur where \(g'(x) = 0\), at \(x = -2\), \(x = 0\), and \(x = 2\). 6. Figure 2 shows \(g'(-1) = 3\), so \(x = -1\) works.

Answer

a) \(g(2) = -3\) b) \(0\) c) \(-3\) d) \(x = 0\) e) \(x = -2\), \(x = 0\), and \(x = 2\) f) \(x = -1\)
53369612
The graph of a function \(f\) has a special point at \(x=-1\). 1) Does \(f^{\prime}\) have a zero at \(x=-1\)? Justify your answer. 2) Describe the general shape of \(f^{\prime}\) near \(x=-1\). Does \(f^{\prime}\) change sign at \(x=-1\)?
Figure for problem 533696

Hints

- Examine the tangent line at \((-1,-1)\). - Determine whether the function increases or decreases on each side of \(x=-1\). - A derivative can equal zero without changing sign.

Solution

1. Yes. At \(x=-1\), the graph of \(f\) has a horizontal inflection point, so its tangent line is horizontal and \(f^{\prime}(-1)=0\). 2. The function \(f\) is increasing on both sides of \(x=-1\). Thus, \(f^{\prime}(x)>0\) near \(-1\), except that \(f^{\prime}(-1)=0\). The derivative graph touches the x-axis at \(x=-1\) and does not cross it, so there is no sign change.

Answer

1) Yes, \(f^{\prime}(-1)=0\). 2) No. The derivative is positive on both sides of \(x=-1\), so its graph touches the x-axis without changing sign.
53369712
The graph of a fourth-degree polynomial \(f\) is shown. 1) Find all inputs where \(f^{\prime}(x)=0\). 2) What is the minimum number of local extrema of \(f^{\prime}\)? Justify your answer using the inflection points of \(f\).
Figure for problem 533697

Hints

- Count the local maxima and minima of \(f\). - A horizontal tangent line gives a zero of \(f^{\prime}\). - An inflection point of \(f\) corresponds to a local extremum of \(f^{\prime}\).

Solution

1. The derivative is zero where the graph of \(f\) has horizontal tangent lines. The graph has local minima at \(x=-2\) and \(x=2\) and a local maximum at \(x=0\). Therefore, \(f^{\prime}(x)=0\) at \(x=-2\), \(x=0\), and \(x=2\). 2. The graph of \(f\) changes concavity once between \(-2\) and \(0\) and once between \(0\) and \(2\). At each inflection point of \(f\), the slope function \(f^{\prime}\) has a local extremum. Thus, \(f^{\prime}\) has at least two local extrema.

Answer

1) \(x=-2\), \(x=0\), and \(x=2\) 2) At least \(2\) local extrema
53370012
The graph of a periodic function \(f\) is shown. 1) Within the displayed interval, find all inputs where the graph of \(f^{\prime}\) crosses the x-axis. 2) At what input in \([-4,4]\) does \(f^{\prime}\) appear to reach its greatest value? Justify your answer using the steepness of \(f\).
Figure for problem 533700

Hints

- Locate the local maximum and local minimum of \(f\). - The derivative is zero at horizontal tangent lines. - Look for the point where the graph rises most steeply.

Solution

1. The derivative is zero at the local extrema of \(f\). The graph has a local minimum at \(x=-\frac{\pi}{2}\) and a local maximum at \(x=\frac{\pi}{2}\). Therefore, the graph of \(f^{\prime}\) crosses the x-axis at those two inputs. 2. The derivative is greatest where the graph of \(f\) rises most steeply. This occurs at the origin, so \(f^{\prime}\) reaches its greatest value at \(x=0\).

Answer

1) \(x=-\frac{\pi}{2}\) and \(x=\frac{\pi}{2}\) 2) \(x=0\)
53371112
The graph of \(f\) is shown. Decide whether each statement about \(f^{\prime}\) is true or false. Briefly justify each decision. (1) \(f^{\prime}(0)\) is positive. (2) The graph of \(f^{\prime}\) has exactly two zeros in the displayed interval. (3) On \([1.5,3]\), the graph of \(f^{\prime}\) lies below the x-axis. (4) \(f^{\prime}(2)=f^{\prime}(-2)\). (5) The graph of \(f^{\prime}\) passes through the origin.
Figure for problem 533711

Hints

- The derivative gives the tangent slope of \(f\). - Local extrema of \(f\) produce zeros of \(f^{\prime}\). - Increasing and decreasing intervals determine the sign of the derivative. - Use the symmetry of the original graph to infer the symmetry of its derivative.

Solution

1. Statement (1) is true. The graph of \(f\) is increasing at \(x=0\), so \(f^{\prime}(0)>0\). 2. Statement (2) is true. The graph has two local extrema, near \(x=-1.4\) and \(x=1.4\). The tangent line is horizontal at each point, so \(f^{\prime}\) has exactly two zeros. 3. Statement (3) is true. The graph of \(f\) is decreasing on \([1.5,3]\), so \(f^{\prime}(x)<0\) throughout that interval. 4. Statement (4) is true. The graph of \(f\) has point symmetry about \((0,1)\), so its derivative is symmetric about the y-axis. Therefore, \(f^{\prime}(2)=f^{\prime}(-2)\). 5. Statement (5) is false. Passing through the origin would require \(f^{\prime}(0)=0\), but the graph of \(f\) has positive slope at \(x=0\).

Answer

(1) True (2) True (3) True (4) True (5) False
53371212
The graph of \(g\) is shown. Which statements about \(g^{\prime}\) are true? Justify your choices. (1) \(g^{\prime}(0)=0\). (2) \(g^{\prime}(x)>0\) for every \(x<0\). (3) The derivative \(g^{\prime}\) has exactly two zeros on \([-4,4]\). (4) \(g^{\prime}(1)<0\). (5) The graph of \(g^{\prime}\) is symmetric about the origin.
Figure for problem 533712

Hints

- Find all horizontal tangent lines on the graph. - The derivative is positive where the function is increasing and negative where it is decreasing. - Recall the derivative symmetry associated with an even function.

Solution

1. Statement (1) is true. The graph of \(g\) has a local maximum at \(x=0\), so the tangent line is horizontal and \(g^{\prime}(0)=0\). 2. Statement (2) is true. The function is increasing for every \(x<0\), so \(g^{\prime}(x)>0\) there. 3. Statement (3) is false. The only horizontal tangent line in \([-4,4]\) occurs at \(x=0\), so \(g^{\prime}\) has exactly one zero. 4. Statement (4) is true. The graph is decreasing for \(x>0\), so \(g^{\prime}(1)<0\). 5. Statement (5) is true. The graph of \(g\) is symmetric about the y-axis, so \(g\) is even and \(g^{\prime}\) is odd. Therefore, the derivative graph is symmetric about the origin.

Answer

(1) True (2) True (3) False (4) True (5) True
53372012
The graph of a fourth-degree polynomial \(f\) is shown. a) Find all inputs where \(f^{\prime}(x)=0\). b) Describe the graph of \(f^{\prime}\), using the monotonicity of \(f\).
Figure for problem 533720

Hints

- Horizontal tangent lines on \(f\) give zeros of \(f^{\prime}\). - Determine whether \(f\) increases or decreases on each interval between its extrema. - The derivative of a fourth-degree polynomial is cubic. - Use the symmetry of \(f\) to check the symmetry of \(f^{\prime}\).

Solution

1. The graph of \(f\) has local maxima at \(x=-2\) and \(x=2\) and a local minimum at \(x=0\). Therefore, \(f^{\prime}(-2)=0\), \(f^{\prime}(0)=0\), and \(f^{\prime}(2)=0\). 2. The function increases for \(x<-2\), decreases for \(-2<x<0\), increases for \(0<x<2\), and decreases for \(x>2\). Thus, \(f^{\prime}\) has the sign pattern positive, negative, positive, negative across those intervals. 3. Since \(f\) is a fourth-degree polynomial, \(f^{\prime}\) is cubic. It is an origin-symmetric cubic that crosses the x-axis at \(x=-2\), \(x=0\), and \(x=2\) with the sign pattern positive, negative, positive, negative from left to right.

Answer

a) \(x=-2\), \(x=0\), and \(x=2\) b) An origin-symmetric cubic crossing the x-axis at \(x=-2\), \(x=0\), and \(x=2\), with signs \(+,-,+,-\) from left to right.
53372112
The graph of a cubic function \(f\) has a horizontal inflection point at \(x=1\). Describe the graph of \(f^{\prime}\). Explain how the horizontal inflection point appears on the derivative graph.
Figure for problem 533721

Hints

- Determine the tangent slope at a horizontal inflection point. - Check whether the original function is increasing or decreasing on each side. - A zero without a sign change appears as a touch rather than a crossing of the x-axis.

Solution

1. At the horizontal inflection point, the tangent line is horizontal, so \(f^{\prime}(1)=0\). 2. The graph of \(f\) is increasing on both sides of \(x=1\), so \(f^{\prime}(x)>0\) for \(x\ne1\). 3. Because the displayed function is cubic, its derivative is quadratic. The derivative graph is an upward-opening parabola with vertex \((1,0)\); the visible slopes of \(f\) determine its vertical scale. 4. The horizontal inflection point of \(f\) appears as a zero of \(f^{\prime}\) where the derivative graph touches the x-axis without changing sign.

Answer

The derivative graph is an upward-opening parabola with vertex \((1,0)\). It touches the x-axis there without changing sign.
53377812
The graph of \(f\) is shown with marked inputs \(x_A=-1\), \(x_B=1\), \(x_C=2\), and \(x_D=4\). Match an input to each description. 1) The function is decreasing and the graph is concave up. 2) The function is increasing and the graph is concave down. 3) The slope of \(f\) is at its minimum value.
Figure for problem 533778

Hints

- Use the sign of \(f^{\prime}\) to decide whether the graph is increasing or decreasing. - Use the sign of \(f^{\prime\prime}\) to decide whether the graph is concave up or concave down. - The minimum value of \(f^{\prime}\) occurs where the graph has its steepest downward slope.

Solution

1. At \(x_A=-1\), the graph is increasing, so \(f^{\prime}(-1)>0\), and it is concave down, so \(f^{\prime\prime}(-1)<0\). Thus, \(x_A\) matches description 2. 2. At \(x_B=1\), the graph has an inflection point where the tangent slope is most negative. Thus, \(f^{\prime}\) has its minimum value there, so \(x_B\) matches description 3. 3. At \(x_C=2\), the graph is decreasing, so \(f^{\prime}(2)<0\), and it is concave up, so \(f^{\prime\prime}(2)>0\). Thus, \(x_C\) matches description 1. 4. At \(x_D=4\), the graph is increasing and concave up, so it does not match any listed description.

Answer

1) \(x_C=2\) 2) \(x_A=-1\) 3) \(x_B=1\)
53390212
The graph of \(f(x)=3-\frac{2}{x^2}\) is shown. Analyze the tangent-slope function for large positive inputs. What value does the slope approach as \(x\to\infty\)? Describe the behavior of \(f^{\prime}\) for \(x>0\).
Figure for problem 533902

Hints

- Examine how the graph approaches its horizontal asymptote. - Tangent slopes approach zero when a graph becomes nearly horizontal. - Determine whether the right branch is increasing or decreasing. - Observe whether the tangent slopes become larger or smaller.

Solution

1. As \(x\to\infty\), the graph of \(f\) approaches the horizontal asymptote \(y=3\). Its tangent lines become nearly horizontal, so \(\lim_{x\to\infty}f^{\prime}(x)=0\). 2. For \(x>0\), the function is increasing, so \(f^{\prime}(x)>0\). 3. The tangent lines become less steep as \(x\) increases. Therefore, \(f^{\prime}\) is strictly decreasing for \(x>0\) and approaches the x-axis from above. The line \(y=0\) is a horizontal asymptote of the derivative graph.

Answer

For \(x>0\), \(f^{\prime}(x)>0\) and \(f^{\prime}\) is strictly decreasing. As \(x\to\infty\), \(f^{\prime}(x)\to0\) from above.
53420012
Graph B shows a function \(g\). Decide whether graph 3 or graph 4 represents \(g^{\prime}\). Justify your choice by comparing monotonicity intervals and local extrema.
Figure for problem 534200

Hints

- Locate the local maximum and local minimum of \(g\). - The derivative must be zero at those inputs. - Determine the sign of the derivative between the extrema. - Select the candidate with the matching sign pattern.

Solution

1. The graph of \(g\) has a local maximum near \(x=-1.73\) and a local minimum near \(x=1.73\). 2. Therefore, \(g^{\prime}\) must have zeros near those inputs. Both candidate graphs have the required zeros. 3. Between the two extrema, \(g\) is decreasing, so \(g^{\prime}(x)<0\) there. 4. Graph 3 lies below the x-axis between its zeros, while graph 4 lies above it. Therefore, graph 3 represents \(g^{\prime}\).

Answer

Graph 3 represents \(g^{\prime}\).
53421312
The graph of a fourth-degree polynomial \(f\) is shown. a) Find the zeros of \(f^{\prime}\) from the graph. b) Describe the graph of \(f^{\prime}\). Explain how the graph of \(f\) tells you whether \(f^{\prime}\) is above or below the x-axis.
Figure for problem 534213

Hints

- Mark every input where the graph has a horizontal tangent line. - Determine whether \(f\) increases or decreases on each interval. - The derivative of a fourth-degree polynomial is cubic. - A steeper graph corresponds to a derivative value farther from zero.

Solution

1. Zeros of \(f^{\prime}\) occur where \(f\) has horizontal tangent lines. The graph has local minima at \(x=-2\) and \(x=2\) and a local maximum at \(x=0\). Thus, the zeros are \(x=-2\), \(x=0\), and \(x=2\). 2. For \(x<-2\), \(f\) is decreasing, so \(f^{\prime}(x)<0\). For \(-2<x<0\), \(f\) is increasing, so \(f^{\prime}(x)>0\). For \(0<x<2\), \(f\) is decreasing, so \(f^{\prime}(x)<0\). For \(x>2\), \(f\) is increasing, so \(f^{\prime}(x)>0\). 3. Since \(f\) is a fourth-degree polynomial, \(f^{\prime}\) is cubic. Its graph crosses the x-axis at \(-2\), \(0\), and \(2\) with the sign pattern negative, positive, negative, positive.

Answer

a) \(x=-2\), \(x=0\), and \(x=2\) b) The derivative graph is cubic. It lies below the x-axis where \(f\) is decreasing and above the x-axis where \(f\) is increasing.
53421412
The graph of a polynomial function \(f\) is shown. Determine the input where \(f^{\prime}\) has a local extremum, and describe the graph of \(f^{\prime}\). Explain the behavior of \(f^{\prime}\) near the origin.
Figure for problem 534214

Hints

- A local extremum of \(f^{\prime}\) occurs where the tangent slope of \(f\) is largest or smallest. - Look for the inflection point of \(f\). - Use the local extrema of \(f\) to locate zeros of \(f^{\prime}\). - The derivative of a cubic polynomial is quadratic.

Solution

1. The graph of \(f\) has a local maximum at \(x=-2\) and a local minimum at \(x=2\). Therefore, \(f^{\prime}(-2)=0\) and \(f^{\prime}(2)=0\). 2. The graph has an inflection point at the origin, where the slope is most negative. The tangent slope there is approximately \(-3\), so \(f^{\prime}\) has a local minimum at \(x=0\). 3. Since \(f\) is cubic, \(f^{\prime}\) is quadratic. Its graph is an upward-opening parabola with zeros at \(x=-2\) and \(x=2\) and a vertex approximately at \((0,-3)\).

Answer

The derivative has a local minimum at \(x=0\). Its graph is an upward-opening parabola with zeros at \(x=-2\) and \(x=2\) and a vertex approximately at \((0,-3)\).
53421512
The graph of \(f\) approaches \(0\) as \(x\to\infty\) and as \(x\to-\infty\). Describe the graph of \(f^{\prime}\), including: - the zeros of \(f^{\prime}\), - the intervals where \(f^{\prime}\) is positive or negative, and - the behavior of \(f^{\prime}\) as \(x\to\infty\) and \(x\to-\infty\).
Figure for problem 534215

Hints

- Find where the original function changes from increasing to decreasing. - A nearly horizontal graph has derivative values near zero. - Locate where the original graph rises and falls most steeply.

Solution

1. The graph of \(f\) has a local maximum at \(x=0\). Therefore, \(f^{\prime}(0)=0\). 2. For \(x<0\), the graph is increasing, so \(f^{\prime}(x)>0\). For \(x>0\), the graph is decreasing, so \(f^{\prime}(x)<0\). 3. Near \(x=-1\), the graph rises most steeply, so \(f^{\prime}\) has a local maximum. Near \(x=1\), the graph falls most steeply, so \(f^{\prime}\) has a local minimum. 4. As \(x\to\pm\infty\), the graph of \(f\) becomes nearly horizontal. Therefore, \(f^{\prime}(x)\to0\).

Answer

The derivative has a zero at \(x=0\). It is positive for \(x<0\), negative for \(x>0\), and approaches \(0\) as \(x\to\pm\infty\). Its graph has a local maximum at a negative input and a local minimum at the corresponding positive input.
53421912
The graph of \(f\) is shown. Decide which statements about \(f^{\prime}\) are true. (1) On \((-2,2)\), the graph of \(f^{\prime}\) lies above the x-axis. (2) \(f^{\prime}(-2)=f^{\prime}(2)\). (3) \(f^{\prime}(0)<f^{\prime}(4)\). (4) The derivative \(f^{\prime}\) has a local extremum at \(x=0\).
Figure for problem 534219

Hints

- Use the monotonicity of \(f\) to determine the sign of \(f^{\prime}\). - Horizontal tangent lines give zeros of the derivative. - Compare a negative slope with a positive slope. - An inflection point of \(f\) corresponds to a local extremum of \(f^{\prime}\).

Solution

1. Statement (1) is false. The function \(f\) is decreasing on \((-2,2)\), so \(f^{\prime}(x)<0\) and its graph lies below the x-axis. 2. Statement (2) is true. The graph has horizontal tangent lines at the local maximum \(x=-2\) and the local minimum \(x=2\). Therefore, \(f^{\prime}(-2)=0=f^{\prime}(2)\). 3. Statement (3) is true. At \(x=0\), the graph is decreasing, so \(f^{\prime}(0)<0\). At \(x=4\), it is increasing, so \(f^{\prime}(4)>0\). Thus, \(f^{\prime}(0)<f^{\prime}(4)\). 4. Statement (4) is true. The graph of \(f\) has an inflection point at \(x=0\). Therefore, its slope function \(f^{\prime}\) has a local extremum there.

Answer

(1) False (2) True (3) True (4) True
53422012
The graph of \(f\) is shown. Which statements about \(f^{\prime}\) are correct? (1) For every \(|x|\ge1\), \(f^{\prime}(x)\le0\). (2) \(f^{\prime}(0)=1\). (3) \(f^{\prime}(2)<f^{\prime}(3)\). (4) The derivative has a zero at \(x=1\).
Figure for problem 534220

Hints

- Use increasing and decreasing behavior to determine the derivative sign. - Look for horizontal tangent lines. - Estimate the tangent slope at the origin. - When comparing negative slopes, the value closer to zero is greater.

Solution

1. Statement (1) is true. The graph of \(f\) is decreasing for \(x\le-1\) and for \(x\ge1\). Thus, \(f^{\prime}(x)\le0\) whenever \(|x|\ge1\). 2. Statement (2) is false. From the graph, the tangent slope at the origin is approximately \(2\), not \(1\). 3. Statement (3) is true. For \(x>1\), the graph is decreasing but becomes flatter as \(x\) increases. Thus, the negative slope at \(x=3\) is closer to zero than the negative slope at \(x=2\), so \(f^{\prime}(2)<f^{\prime}(3)\). 4. Statement (4) is true. The graph has a local maximum at \(x=1\), so the tangent line is horizontal and \(f^{\prime}(1)=0\).

Answer

(1) True (2) False (3) True (4) True
53422712
The graph of a cubic polynomial \(f\) is shown. Decide which statements are true. (1) The derivative \(f^{\prime}\) has exactly two zeros in the displayed interval. (2) On \((-1,3)\), the graph of \(f^{\prime}\) lies above the x-axis. (3) The derivative \(f^{\prime}\) has a local extremum at \(x=1\). (4) \(\lim_{x\to\infty}f^{\prime}(x)=\infty\).
Figure for problem 534227

Hints

- Local extrema of \(f\) give zeros of \(f^{\prime}\). - Use increasing and decreasing intervals to determine the derivative sign. - An inflection point of \(f\) corresponds to a local extremum of \(f^{\prime}\). - Consider the degree and leading coefficient of the derivative.

Solution

1. Statement (1) is true. The graph has a local maximum at \(x=-1\) and a local minimum at \(x=3\), so \(f^{\prime}\) has zeros at those two inputs. 2. Statement (2) is false. The graph of \(f\) is decreasing on \((-1,3)\), so \(f^{\prime}(x)<0\) and the derivative graph lies below the x-axis. 3. Statement (3) is true. The graph of \(f\) has an inflection point at \(x=1\), so \(f^{\prime}\) has a local extremum there. 4. Statement (4) is true. The cubic has a positive leading coefficient, so its derivative is an upward-opening quadratic. Therefore, \(f^{\prime}(x)\to\infty\) as \(x\to\infty\).

Answer

(1) True (2) False (3) True (4) True
53422912
The graph of \(f\) is shown. Which expression represents \(f^{\prime}\)? Justify your choice. A) \(f^{\prime}(x)=-0.3x^2+0.6x+0.9\) B) \(f^{\prime}(x)=0.3x^2-0.6x-0.9\) C) \(f^{\prime}(x)=-0.6x+0.6\) D) \(f^{\prime}(x)=-0.1x^2+0.3x+0.9\)
Figure for problem 534229

Hints

- Find the local extrema of \(f\). - The derivative must be zero at those inputs. - Use the increasing and decreasing intervals to determine the sign of the derivative. - The derivative of a cubic polynomial is quadratic.

Solution

1. The graph has a local minimum at \(x=-1\) and a local maximum at \(x=3\). Therefore, \(f^{\prime}\) must have zeros at \(x=-1\) and \(x=3\). 2. Options A and B have those two zeros. Option C is linear and has only one zero, and option D has different zeros. 3. Between \(-1\) and \(3\), the graph of \(f\) is increasing, so \(f^{\prime}(x)>0\) there. 4. At \(x=0\), option A gives \(0.9>0\), while option B gives \(-0.9<0\). Therefore, option A has the correct sign pattern.

Answer

A) \(f^{\prime}(x)=-0.3x^2+0.6x+0.9\)
53423812
The graph of \(f\) is shown. Decide whether each statement about \(f^{\prime}\) is true or false. (1) \(f^{\prime}(-1)>0\). (2) \(f^{\prime}(0)=0\). (3) On \([0,1.5]\), the graph of \(f^{\prime}\) lies above the x-axis. (4) The derivative has a zero near \(x=1.7\). (5) The slope of \(f\) at \(x=2\) is negative. (6) The derivative \(f^{\prime}\) has at least three zeros.
Figure for problem 534238

Hints

- The derivative sign indicates whether the original graph is increasing or decreasing. - Horizontal tangent lines give zeros of the derivative. - Check the entire stated interval, including its endpoints. - Count all local extrema of the original graph.

Solution

1. Statement (1) is true. The graph is increasing at \(x=-1\), so \(f^{\prime}(-1)>0\). 2. Statement (2) is true. The graph has a local maximum at \(x=0\), so \(f^{\prime}(0)=0\). 3. Statement (3) is false. At \(x=0\), the derivative equals zero, and for \(0<x\le1.5\), the graph of \(f\) is decreasing, so \(f^{\prime}(x)<0\). 4. Statement (4) is true. The graph has a local minimum near \(x=1.73\), so \(f^{\prime}\) has a zero there. 5. Statement (5) is false. The graph is increasing at \(x=2\), so \(f^{\prime}(2)>0\). 6. Statement (6) is true. The graph has three horizontal tangent lines, so \(f^{\prime}\) has three zeros.

Answer

(1) True (2) True (3) False (4) True (5) False (6) True
53423912
The graph of \(g\) is shown. a) At what inputs is \(g^{\prime}(x)=0\)? b) Is \(g^{\prime}(x)\) positive or negative on \((0,2)\)? Justify your answer using the graph of \(g\). c) Which value is greater, \(g^{\prime}(-1)\) or \(g^{\prime}(1)\)? Briefly explain.
Figure for problem 534239

Hints

- Local extrema of \(g\) give zeros of \(g^{\prime}\). - The derivative is negative where the function is decreasing. - Compare the signs of the tangent slopes at \(x=-1\) and \(x=1\).

Solution

1. The derivative is zero where the graph has horizontal tangent lines. The graph has a local maximum at \(x=0\) and a local minimum at \(x=2\). Thus, \(g^{\prime}(0)=0\) and \(g^{\prime}(2)=0\). 2. The graph of \(g\) is decreasing on \((0,2)\), so \(g^{\prime}(x)<0\) throughout that interval. 3. At \(x=-1\), the graph is increasing, so \(g^{\prime}(-1)>0\). At \(x=1\), it is decreasing, so \(g^{\prime}(1)<0\). Therefore, \(g^{\prime}(-1)>g^{\prime}(1)\).

Answer

a) \(x=0\) and \(x=2\) b) Negative: \(g^{\prime}(x)<0\) on \((0,2)\). c) \(g^{\prime}(-1)>g^{\prime}(1)\).
53424712
The graph of \(h\) is shown. Decide whether each statement about \(h^{\prime}\) is true or false, and justify your decision. (1) \(h^{\prime}(-2)=0\). (2) \(h^{\prime}(0)>0\). (3) On \([-1,1]\), the graph of \(h^{\prime}\) lies below the x-axis. (4) The derivative \(h^{\prime}\) has exactly two zeros.
Figure for problem 534247

Hints

- The derivative is the tangent slope of the original graph. - Use increasing and decreasing intervals to determine the derivative sign. - Horizontal tangent lines produce zeros of the derivative. - Count all local extrema in the displayed interval.

Solution

1. Statement (1) is true. The graph has a local maximum at \(x=-2\), so the tangent line is horizontal and \(h^{\prime}(-2)=0\). 2. Statement (2) is false. The graph is decreasing at \(x=0\), so \(h^{\prime}(0)<0\). 3. Statement (3) is true. The graph is strictly decreasing throughout \([-1,1]\), so \(h^{\prime}(x)<0\) there and the derivative graph lies below the x-axis. 4. Statement (4) is true. The graph has exactly two horizontal tangent lines, at the local maximum \(x=-2\) and the local minimum \(x=2\). Therefore, \(h^{\prime}\) has exactly two zeros.

Answer

(1) True (2) False (3) True (4) True
53424912
The graph of \(g\) is shown with three candidate derivative graphs, A, B, and C. Which graph represents \(g^{\prime}\)? Explain why the other two graphs cannot be correct.
Figure for problem 534249

Hints

- Count all horizontal tangent lines on the graph of \(g\). - Match their x-coordinates to zeros of the candidates. - Check whether \(g\) is increasing or decreasing on each interval. - Eliminate any candidate with the wrong sign.

Solution

1. The fourth-degree graph of \(g\) has local minima at \(x=-2\) and \(x=2\) and a local maximum at \(x=0\). Therefore, \(g^{\prime}\) must have zeros at \(x=-2\), \(x=0\), and \(x=2\). 2. Graph A has only two zeros, so it cannot represent \(g^{\prime}\). 3. Graph C has three zeros, but they occur at different inputs. Its sign pattern also does not match: for \(x<-2\), the graph of \(g\) is decreasing, so \(g^{\prime}(x)\) must be negative. 4. Graph B has the required zeros and sign pattern. Therefore, graph B represents \(g^{\prime}\).

Answer

Graph B represents \(g^{\prime}\). Graph A has too few zeros, and graph C has zeros at the wrong inputs and the wrong sign pattern.
53429212
The graph of \(f\) has seven marked inputs, \(x_1\) through \(x_7\). Identify the marked input or inputs where: a) \(f(x)\) is greatest and where it is least, b) \(f^{\prime}(x)\) is greatest and where it is least, and c) the graph is concave down, so \(f^{\prime\prime}(x)<0\).
Figure for problem 534292

Hints

- Function values are compared by the vertical positions of the marked points. - Derivative values are compared by tangent-line steepness and direction. - A steep downward tangent has a large negative derivative. - Concave down means tangent slopes decrease as \(x\) increases.

Solution

1. Compare the heights of the marked points. The greatest marked function values occur at \(x_1\) and \(x_7\). The least marked values occur at the local minima \(x_2\) and \(x_6\). 2. The derivative is greatest where the graph rises most steeply, at \(x_7\). It is least where the graph falls most steeply, at \(x_1\). 3. The graph is concave down near its local maximum, which is the marked point \(x_4\). The points \(x_3\) and \(x_5\) are approximately inflection points, while the other marked points are in concave-up regions.

Answer

a) Greatest at \(x_1\) and \(x_7\); least at \(x_2\) and \(x_6\) b) Greatest at \(x_7\); least at \(x_1\) c) Concave down at \(x_4\)
53429312
The graph of \(g\) has marked inputs \(x_1\) through \(x_6\). Use the graph to determine: a) where \(g(x)\) reaches its maximum in the displayed interval, b) where the instantaneous rate of change \(g^{\prime}(x)\) is smallest, and c) where the graph has an inflection point, so \(g^{\prime\prime}(x)=0\).
Figure for problem 534293

Hints

- The maximum occurs at the highest marked point. - The smallest derivative occurs where the graph has its steepest downward tangent. - An inflection point is where the graph changes concavity.

Solution

1. The highest marked point is \(x_3\), so \(g(x)\) reaches its maximum there. 2. The derivative is smallest where the graph falls most steeply. Among the marked points on the decreasing part of the graph, this occurs at \(x_5\). 3. At \(x_5\), the graph changes from concave down to concave up. Therefore, \(x_5\) is an inflection point and \(g^{\prime\prime}(x_5)=0\).

Answer

a) \(x_3\) b) \(x_5\) c) \(x_5\)
53435412
Graphs A, B, and C are possible graphs of \(f^{\prime}\). The function \(f\) is defined for all real numbers and has exactly two local extrema on \([-4,4]\): a local minimum at \(x=-2\) and a local maximum at \(x=2\). Decide which graph represents \(f^{\prime}\). Explain why the other two graphs cannot be correct.
Figure for problem 534354

Hints

- A local extremum of \(f\) corresponds to a zero of \(f^{\prime}\). - At a local minimum, the derivative changes from negative to positive. - At a local maximum, the derivative changes from positive to negative. - Check both the number of zeros and the direction of each sign change.

Solution

1. At the local minimum \(x=-2\), the derivative must be zero and change sign from negative to positive. 2. At the local maximum \(x=2\), the derivative must be zero and change sign from positive to negative. 3. Graph C has only one zero, so it cannot represent the derivative. 4. Graph B has zeros at \(-2\) and \(2\), but its sign changes correspond to a maximum at \(-2\) and a minimum at \(2\), the reverse of the given information. 5. Graph A has zeros at \(-2\) and \(2\), with a negative-to-positive sign change at \(-2\) and a positive-to-negative sign change at \(2\). Therefore, graph A represents \(f^{\prime}\).

Answer

Graph A represents \(f^{\prime}\).
53439212
Panel a) shows a function \(k\). Panels b), c), and d) show three possible graphs of \(k^{\prime}\). Which panel represents \(k^{\prime}\)? Justify your choice by comparing geometric features of the function and derivative graphs.
Figure for problem 534392

Hints

- Horizontal tangent lines on \(k\) give zeros of \(k^{\prime}\). - Determine where \(k\) is increasing or decreasing. - The derivative of a cubic polynomial is quadratic. - Check the sign of each candidate between the two zeros.

Solution

1. The graph of \(k\) has a local maximum at \(x=0\) and a local minimum at \(x=2\). Therefore, \(k^{\prime}\) must have zeros at \(x=0\) and \(x=2\). 2. Panel d) is a line with only one zero. Also, the derivative of a cubic function must be quadratic, so panel d) cannot be correct. 3. Panels b) and c) are parabolas with zeros at \(x=0\) and \(x=2\). 4. The graph of \(k\) is decreasing for \(0<x<2\), so \(k^{\prime}(x)<0\) on that interval. 5. Panel b) lies below the x-axis between the zeros, while panel c) lies above it. Therefore, panel b) represents \(k^{\prime}\).

Answer

Panel b) represents \(k^{\prime}\).
53448412
The graph of \(f\) is shown. Decide whether each statement is true or false. (1) \(f^{\prime}\) has exactly two zeros. (2) The graph of \(f\) has exactly three inflection points in the displayed interval. (3) \(f^{\prime}(0)>0\). (4) The graph of \(f^{\prime}\) is symmetric about the origin. (5) \(f^{\prime\prime}(1)>0\).
Figure for problem 534484

Hints

- Local extrema of \(f\) give zeros of \(f^{\prime}\). - Inflection points occur where the graph changes concavity. - The first derivative gives tangent slope. - The derivative of an odd function is even. - Concave down corresponds to a negative second derivative.

Solution

1. Statement (1) is true. The graph of \(f\) has a local minimum at \(x=-2\) and a local maximum at \(x=2\), so \(f^{\prime}\) has exactly two zeros. 2. Statement (2) is true. The graph changes concavity near \(x=-3.5\), at \(x=0\), and near \(x=3.5\), giving three inflection points in the displayed interval. 3. Statement (3) is true. The graph is increasing at the origin, so \(f^{\prime}(0)>0\). 4. Statement (4) is false. The graph of \(f\) is symmetric about the origin, so \(f\) is odd and \(f^{\prime}\) is even. Therefore, the derivative graph is symmetric about the y-axis. 5. Statement (5) is false. At \(x=1\), the graph is concave down, so \(f^{\prime\prime}(1)<0\).

Answer

(1) True (2) True (3) True (4) False (5) False
53450412
The graph of \(f\) is shown. 1) Use the graph to estimate the inputs where \(f^{\prime}\) has zeros. 2) Describe the graph of \(f^{\prime}\), paying particular attention to the monotonicity of \(f\).
Figure for problem 534504

Hints

- Find the horizontal tangent lines on the graph of \(f\). - Use increasing and decreasing intervals to determine the derivative sign. - Identify where \(f\) has its most negative slope. - The derivative of a cubic polynomial is quadratic.

Solution

1. The derivative is zero at the local extrema of \(f\). From the graph, these occur near \(x=-1.4\) and \(x=1.4\). 2. The graph of \(f\) is increasing for \(x<-1.4\), decreasing for \(-1.4<x<1.4\), and increasing for \(x>1.4\). Therefore, \(f^{\prime}\) is positive, then negative, then positive across those intervals. 3. Since \(f\) is cubic, \(f^{\prime}\) is an upward-opening parabola. Its minimum occurs at \(x=0\), where the graph of \(f\) has its most negative slope.

Answer

1) The zeros are approximately \(x=-1.4\) and \(x=1.4\). 2) The derivative graph is an upward-opening parabola, positive outside the two zeros and negative between them, with a minimum at \(x=0\).
53450812
The graph of a bell-shaped function \(f\) is shown. 1) Describe the graph of \(f^{\prime}\). 2) Find the x-coordinates of the local extrema of \(f^{\prime}\). What do these inputs represent on the graph of \(f\)?
Figure for problem 534508

Hints

- The derivative is zero at the maximum of the bell curve. - Determine the derivative sign from increasing and decreasing behavior. - The extrema of the derivative occur where the original graph is steepest. - Use symmetry to check your description.

Solution

1. The graph of \(f\) is symmetric about the y-axis and has a maximum at \(x=0\). Therefore, \(f^{\prime}(0)=0\). The function increases for \(x<0\), so \(f^{\prime}(x)>0\), and decreases for \(x>0\), so \(f^{\prime}(x)<0\). 2. The local extrema of \(f^{\prime}\) occur where the graph of \(f\) is steepest. These are the inflection points of \(f\), at approximately \(x=-1\) and \(x=1\). 3. Thus, the derivative graph rises from values near zero to a local maximum near \(x=-1\), crosses the x-axis at \(x=0\), falls to a local minimum near \(x=1\), and approaches zero from below.

Answer

1) The derivative is positive for \(x<0\), zero at \(x=0\), and negative for \(x>0\), approaching \(0\) at both ends. 2) The local extrema of \(f^{\prime}\) occur at approximately \(x=-1\) and \(x=1\). These are the inflection points of \(f\).
53453012
The graph of \(h\) is shown. Determine the number of zeros of \(h^{\prime}\) and the number of zeros of \(h^{\prime\prime}\).
Figure for problem 534530

Hints

- Count all horizontal tangent lines. - Count all changes in concavity.

Solution

1. The graph has one local maximum at \(x=0\). The tangent line is horizontal there, so \(h^{\prime}\) has exactly \(1\) zero. 2. The graph changes concavity once on each side of the maximum. Therefore, it has two inflection points and \(h^{\prime\prime}\) has exactly \(2\) zeros.

Answer

\(h^{\prime}\) has \(1\) zero, and \(h^{\prime\prime}\) has \(2\) zeros.
53453212
Analyze the graph of \(p\). Determine the number of zeros of \(p^{\prime}\) and the number of zeros of \(p^{\prime\prime}\).
Figure for problem 534532

Hints

- Count points with horizontal tangent lines. - Check for a concavity change within each continuous branch. - Do not count a vertical asymptote as an inflection point.

Solution

1. The graph has one local maximum on the left branch and one local minimum on the right branch. Therefore, \(p^{\prime}\) has \(2\) zeros. 2. Neither branch changes concavity. The function is not defined at the vertical asymptote, so no change across it is an inflection point. Therefore, \(p^{\prime\prime}\) has \(0\) zeros.

Answer

\(p^{\prime}\) has \(2\) zeros, and \(p^{\prime\prime}\) has \(0\) zeros.
53453412
Analyze the graph of \(r\). Determine the number of zeros of \(r^{\prime}\) and the number of zeros of \(r^{\prime\prime}\).
Figure for problem 534534

Hints

- Look for horizontal tangent lines. - Identify any point where a continuous branch changes concavity. - Analyze the separate branches around the vertical asymptotes.

Solution

1. The function is strictly decreasing on every interval of its domain and has no horizontal tangent lines. Therefore, \(r^{\prime}\) has \(0\) zeros. 2. On the middle branch, the graph changes concavity at the origin. Thus, \((0,0)\) is an inflection point and \(r^{\prime\prime}\) has one zero. The outer branches have no additional concavity changes.

Answer

\(r^{\prime}\) has \(0\) zeros, and \(r^{\prime\prime}\) has \(1\) zero.
53458212
The graph shows a function \(g\) and its derivative \(g^{\prime}\). The curves are labeled \(k\) and \(m\). a) Decide which curve represents \(g\) and which represents \(g^{\prime}\). Justify your choice. b) Find the slope of the graph of \(g\) at \(x=3\). c) At what x-value greater than \(0\) do \(g\) and \(g^{\prime}\) have the same value?
Figure for problem 534582

Hints

- Consider the degree of the derivative of a quadratic function. - A local extremum of the original function occurs where its derivative is zero. - Read the derivative value at \(x=3\) to find the tangent slope. - The function and derivative have the same value where their graphs intersect.

Solution

1. Curve \(k\) is a parabola and curve \(m\) is a line. Since the derivative of a quadratic function is linear, \(k\) represents \(g\) and \(m\) represents \(g^{\prime}\). This also agrees with the local minimum of \(k\) and the zero of \(m\) at \(x=0\). 2. The slope of \(g\) at \(x=3\) is \(g^{\prime}(3)\). From curve \(m\), \(g^{\prime}(3)=1.5\). 3. The curves intersect for \(x>0\) at \(x=2\). At that point, \(g(2)=g^{\prime}(2)=1\).

Answer

a) Curve \(k\) represents \(g\), and curve \(m\) represents \(g^{\prime}\). b) \(1.5\) c) \(x=2\)
53486812
The graph of a quartic polynomial \(f\) is shown. Its local minima occur at \(x\approx -1.73\) and \(x\approx 1.73\), and its local maximum occurs at \(x=0\). The inflection points are \(W_1(-1,2.5)\) and \(W_2(1,2.5)\). a) Give the zeros of \(f^{\prime}\) and \(f^{\prime\prime}\). b) On \(0\leq x\leq 1.73\), determine where the graph of \(f\) is decreasing most steeply. Justify your answer. c) Describe the qualitative shape of the graph of \(f^{\prime}\).
Figure for problem 534868

Hints

- Where does the graph of \(f\) have horizontal tangent lines? - How are the inflection points of \(f\) related to the local extrema of \(f^{\prime}\)? - On the interval where \(f\) is decreasing, where is its slope most negative? - Use the degree and symmetry of \(f\) to describe \(f^{\prime}\).

Solution

1. The zeros of \(f^{\prime}\) occur at the local extrema of \(f\). Thus, \(f^{\prime}(x)=0\) at \(x\approx -1.73\), \(x=0\), and \(x\approx 1.73\). 2. The zeros of \(f^{\prime\prime}\) occur at the inflection points of \(f\). Thus, \(f^{\prime\prime}(x)=0\) at \(x=-1\) and \(x=1\). 3. On \(0\leq x\leq 1.73\), the graph is decreasing, so the steepest decrease occurs where \(f^{\prime}\) is smallest. The local minimum of \(f^{\prime}\) occurs where \(f^{\prime\prime}=0\), at \(x=1\). 4. Because \(f\) is an even quartic polynomial, \(f^{\prime}\) is an odd cubic polynomial. Its graph is symmetric about the origin, has zeros at \(x\approx -1.73\), \(x=0\), and \(x\approx 1.73\), has a local maximum at \(x=-1\), and has a local minimum at \(x=1\).

Answer

a) Zeros of \(f^{\prime}\): \(x\approx -1.73\), \(x=0\), and \(x\approx 1.73\). Zeros of \(f^{\prime\prime}\): \(x=-1\) and \(x=1\). b) The graph decreases most steeply at \(x=1\), where \(f^{\prime}\) has a local minimum. c) The graph of \(f^{\prime}\) is an odd cubic graph with zeros at \(x\approx -1.73\), \(x=0\), and \(x\approx 1.73\), a local maximum at \(x=-1\), and a local minimum at \(x=1\).
53264112
The graphs of two rational functions, \(f\) in Graph 1 and \(g\) in Graph 2, are shown. a) For \(f\), determine the number of zeros of \(f^{\prime}\) and the number of zeros of \(f^{\prime\prime}\). Briefly justify your answers using geometric features of the graph. b) For \(g\), determine the number of zeros of \(g^{\prime}\) and the number of zeros of \(g^{\prime\prime}\). Briefly justify your answers using geometric features of the graph.
Figure for problem 532641

Hints

- Zeros of the first derivative occur where the graph has horizontal tangent lines. - Zeros of the second derivative can occur at inflection points. - A change across a discontinuity is not an inflection point. - Count each qualifying point within the function domain.

Solution

1. For \(f\), zeros of \(f^{\prime}\) occur at horizontal tangent lines. The graph has one local minimum at \(x=-1\) and one local maximum at \(x=1\), so \(f^{\prime}\) has \(2\) zeros. Zeros of \(f^{\prime\prime}\) correspond to inflection points. The graph changes concavity three times: once on the left side, once at the origin, and once on the right side. Therefore, \(f^{\prime\prime}\) has \(3\) zeros. 2. For \(g\), the graph has one local minimum at \(x=0\), so \(g^{\prime}\) has \(1\) zero. The graph does not change concavity within any interval of its domain. Changes across the vertical asymptotes \(x=-1\) and \(x=1\) are not inflection points because the function is not defined there. Therefore, \(g^{\prime\prime}\) has \(0\) zeros.

Answer

a) \(f^{\prime}\) has \(2\) zeros, and \(f^{\prime\prime}\) has \(3\) zeros. b) \(g^{\prime}\) has \(1\) zero, and \(g^{\prime\prime}\) has \(0\) zeros.
53264612
The graphs of two rational functions are shown: \(f\) in panel a) and \(g\) in panel b). For each function, determine the number of zeros of its first derivative and the number of zeros of its second derivative. Justify your answers using local extrema and concavity.
Figure for problem 532646

Hints

- Zeros of the first derivative occur at horizontal tangent lines. - Zeros of the second derivative can occur where the graph changes concavity. - Do not count a change across a vertical asymptote as an inflection point. - Track each branch from left to right.

Solution

1. In panel a), the graph of \(f\) has one local minimum at \(x=0\), so \(f^{\prime}\) has \(1\) zero. Within each continuous interval of its domain, the graph does not change concavity. The changes across the vertical asymptotes are not inflection points because \(f\) is undefined there. Thus, \(f^{\prime\prime}\) has \(0\) zeros. 2. In panel b), the graph of \(g\) has one local minimum on the left branch and one local maximum on the right branch, so \(g^{\prime}\) has \(2\) zeros. The graph changes concavity once on each branch, so \(g^{\prime\prime}\) has \(2\) zeros.

Answer

a) \(f^{\prime}\) has \(1\) zero, and \(f^{\prime\prime}\) has \(0\) zeros. b) \(g^{\prime}\) has \(2\) zeros, and \(g^{\prime\prime}\) has \(2\) zeros.
53372212
The graph of \(f\) is shown. 1) Record the notable inputs, including local extrema and horizontal inflection points, in a table and give the corresponding values of \(f^{\prime}\). 2) Use this information to describe the graph of \(f^{\prime}\).
Figure for problem 533722

Hints

- Find each point where the graph of \(f\) has a horizontal tangent line. - Distinguish a local extremum from a horizontal inflection point. - Determine the sign of the derivative from the increasing and decreasing intervals. - A sign change produces a crossing; no sign change produces a touch.

Solution

1. The notable points give the following table: <table> <tr><th>Input \(x\)</th><th>Type of point on \(f\)</th><th>Value of \(f^{\prime}(x)\)</th></tr> <tr><td>\(0\)</td><td>Local minimum</td><td>\(0\)</td></tr> <tr><td>\(3\)</td><td>Horizontal inflection point</td><td>\(0\)</td></tr> </table> 2. For \(x<0\), the function is decreasing, so \(f^{\prime}(x)<0\). For \(0<x<3\), the function is increasing, so \(f^{\prime}(x)>0\). For \(x>3\), the function continues increasing, so \(f^{\prime}(x)>0\). 3. The derivative graph crosses the x-axis at \(x=0\), changing from negative to positive. At \(x=3\), it touches the x-axis from above without changing sign. One additional reference value is \(f^{\prime}(1)\approx0.8\).

Answer

The derivative has zeros at \(x=0\) and \(x=3\). At \(x=0\), it changes sign from negative to positive and crosses the x-axis. At \(x=3\), it remains positive on both sides and touches the x-axis.
53453912
The graphs of two functions, \(h\) and \(k\), are shown. For each function, determine the number of zeros of its first derivative and the number of zeros of its second derivative. Justify your answers using the local extrema and inflection points visible in the graphs.
Figure for problem 534539

Hints

- Zeros of the first derivative occur where the graph has a horizontal tangent line. - Zeros of the second derivative can occur where the graph changes concavity. - Analyze each continuous branch separately; a vertical asymptote is not an extremum or an inflection point.

Solution

1. For \(h\), the graph has a local minimum at \(x=-1\) and a local maximum at \(x=1\). These are the two points with horizontal tangent lines, so \(h^{\prime}\) has \(2\) zeros. 2. The graph of \(h\) changes concavity at \(x=-\sqrt{3}\), \(x=0\), and \(x=\sqrt{3}\). Therefore, \(h^{\prime\prime}\) has \(3\) zeros. 3. For \(k\), the graph has one local maximum at \(x=2\). Therefore, \(k^{\prime}\) has \(1\) zero. 4. The right branch of \(k\) changes concavity once, at \(x=3\). The left branch has no concavity change, and the vertical asymptote is not an inflection point. Therefore, \(k^{\prime\prime}\) has \(1\) zero.

Answer

Graph \(h\): \(h^{\prime}\) has \(2\) zeros, and \(h^{\prime\prime}\) has \(3\) zeros. Graph \(k\): \(k^{\prime}\) has \(1\) zero, and \(k^{\prime\prime}\) has \(1\) zero.

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