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Vertex and intercept forms

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5100859
The graph of \(y = 3(x - 4)(x + 2)\) has which vertex? a) \((1, 27)\) b) \((1, -27)\) c) \((-2, 4)\) d) \((-1, -15)\)

Hints

- What key points can you read directly from intercept form? - Where is the axis of symmetry relative to the two zeros? - After finding the vertex's \(x\)-coordinate, how can you find its \(y\)-coordinate?

Solution

1. From intercept form, the zeros are \(x = 4\) and \(x = -2\). 2. The axis of symmetry is halfway between the zeros: \(x = \frac{4 + (-2)}{2} = 1\). 3. Substitute \(x = 1\): \(y = 3(1 - 4)(1 + 2) = 3 \cdot (-3) \cdot 3 = -27\). Therefore, the vertex is \((1, -27)\).

Answer

b) \((1, -27)\)
5145099
Find the vertex of each quadratic function. a) \(f(x) = (x + 3.2)^2 - 1.5\) b) \(g(x) = -(x - 5)^2 + 2\) c) \(h(x) = x^2 + 8.5\)

Hints

- Recall the vertex form \(y = a(x - h)^2 + k\). - Pay close attention to the sign inside the parentheses. - Which term outside the square gives the vertex's \(y\)-coordinate? - If the squared expression is just \(x^2\), what is the horizontal shift?

Solution

1. Compare each function with vertex form \(y = a(x - h)^2 + k\), whose vertex is \((h, k)\). 2. For a), \(f(x) = (x - (-3.2))^2 - 1.5\), so the vertex is \((-3.2, -1.5)\). 3. For b), \(g(x) = -(x - 5)^2 + 2\), so the vertex is \((5, 2)\). 4. For c), \(h(x) = (x - 0)^2 + 8.5\), so the vertex is \((0, 8.5)\).

Answer

a) \((-3.2, -1.5)\) b) \((5, 2)\) c) \((0, 8.5)\)
5145279
Three parabolas are defined by \(f(x)=x^2-5\), \(g(x)=(x+4)^2\), and \(h(x)=(x-1)^2+2\). Match each function to its description and state the vertex of each parabola. 1. The graph is translated only horizontally from \(y=x^2\). 2. The graph is translated only vertically from \(y=x^2\). 3. The graph is translated both horizontally and vertically from \(y=x^2\).

Hints

- Compare each equation with vertex form \(y=(x-h)^2+k\). - How do \(h\) and \(k\) locate the vertex? - If one of the shifts is zero, the graph is not translated in that direction.

Solution

1. For \(f(x)=x^2-5\), the \(-5\) outside the squared expression shifts the graph down \(5\) units. Its vertex is \((0, -5)\), so it matches description 2. 2. For \(g(x)=(x+4)^2\), the \(+4\) inside the squared expression shifts the graph left \(4\) units. Its vertex is \((-4, 0)\), so it matches description 1. 3. For \(h(x)=(x-1)^2+2\), the graph shifts right \(1\) unit and up \(2\) units. Its vertex is \((1, 2)\), so it matches description 3.

Answer

1. \(g(x)=(x+4)^2\), vertex \((-4, 0)\) 2. \(f(x)=x^2-5\), vertex \((0, -5)\) 3. \(h(x)=(x-1)^2+2\), vertex \((1, 2)\)
5145939
The quadratic function \(f\) is defined by \(f(x)=-1.5(x-3)^2+5\). a) State the vertex. b) Determine whether the parabola opens upward or downward and whether it is narrower or wider than \(y=x^2\). Briefly justify your answer. c) Determine the range of \(f\). d) Describe the transformations that map \(y=x^2\) onto the graph of \(f\).

Hints

- Compare the equation with \(y=a(x-h)^2+k\). - What does the sign of \(a\) tell you? - How does \(|a|\) affect the width of the parabola? - Is the vertex a maximum or a minimum?

Solution

1. From vertex form, the vertex is \((3, 5)\). 2. The coefficient is \(a=-1.5\). Since \(a<0\), the parabola opens downward. Since \(|a|=1.5>1\), the graph is narrower than \(y=x^2\). 3. The vertex is the maximum point, so the range is \((-\infty, 5]\). 4. Starting with \(y=x^2\), reflect the graph across the x-axis, apply a vertical stretch by a factor of \(1.5\), shift it \(3\) units right, and shift it \(5\) units up.

Answer

a) \((3, 5)\) b) The parabola opens downward and is narrower than \(y=x^2\). c) \((-\infty, 5]\) d) Reflect across the x-axis, vertically stretch by a factor of \(1.5\), shift \(3\) units right, and shift \(5\) units up.
5152709
A parabolic bridge arch is modeled by \(p(x) = -0.1(x - 10)^2 + 10\), where \(x\) and \(p(x)\) are measured in meters. a) Rewrite the function in standard form. b) Use the standard form to find the zeros and determine the width of the arch at ground level.

Hints

- Expand the squared binomial before distributing the coefficient. - Set the function equal to \(0\) to find the ground-level intercepts. - The width is the distance between the two zeros.

Solution

1. Expand the square: \((x - 10)^2 = x^2 - 20x + 100\). 2. Substitute and simplify: \(p(x) = -0.1(x^2 - 20x + 100) + 10 = -0.1x^2 + 2x - 10 + 10\). Therefore, \(p(x) = -0.1x^2 + 2x\). 3. Set the standard form equal to zero: \(-0.1x^2 + 2x = 0\). Factoring gives \(x(-0.1x + 2) = 0\), so the zeros are \(x = 0\) and \(x = 20\). 4. The distance between the ground-level intercepts is \(20 - 0 = 20\), so the arch is \(20\,\text{m}\) wide.

Answer

a) \(p(x) = -0.1x^2 + 2x\) b) The zeros are \(x = 0\) and \(x = 20\), so the width is \(20\,\text{m}\).
5152779
For each quadratic function, state the vertex and find the zeros. a) \(f(x) = (x + 4)^2 - 9\) b) \(g(x) = -2(x - 3)^2 + 8\)

Hints

- What information can you read directly from vertex form? - How does the sign inside the parentheses determine the vertex's \(x\)-coordinate? - What equation do you solve to find \(x\)-intercepts? - How do you solve an equation of the form \((x - h)^2 = r\)?

Solution

1. For a), vertex form shows the vertex is \((-4, -9)\). Set \((x + 4)^2 - 9 = 0\), so \((x + 4)^2 = 9\). Therefore, \(x + 4 = \pm 3\), giving \(x = -7\) or \(x = -1\). 2. For b), vertex form shows the vertex is \((3, 8)\). Set \(-2(x - 3)^2 + 8 = 0\), so \((x - 3)^2 = 4\). Therefore, \(x - 3 = \pm 2\), giving \(x = 1\) or \(x = 5\).

Answer

a) Vertex \((-4, -9)\); zeros \(x = -7\) and \(x = -1\) b) Vertex \((3, 8)\); zeros \(x = 1\) and \(x = 5\)
5152919
Determine the number of real zeros in each case without calculating. Justify each answer using the vertex and the direction in which the parabola opens. a) \(h(x) = -3(x - 2)^2 + 12\) b) A parabola has vertex \((5, 2)\) and opens upward. c) \(k(x) = (x + 3)^2\)

Hints

- Locate the vertex relative to the x-axis. - Identify whether the parabola opens upward or downward. - Use those two features to decide whether the graph crosses, touches, or misses the x-axis.

Solution

1. For a), the vertex is \((2, 12)\), which is above the x-axis. Because the parabola opens downward, it crosses the x-axis twice. 2. For b), the vertex is above the x-axis and the parabola opens upward, so the entire graph stays above the x-axis. It has no real zeros. 3. For c), the vertex is \((-3, 0)\), which lies on the x-axis. The parabola touches the x-axis once, so it has one real zero.

Answer

a) Two real zeros b) No real zeros c) One real zero
5153309
The cross section of a skateboard ramp is parabolic. Its lowest point is at the origin, \((0, 0)\). At a horizontal distance of \(4.00\,\text{m}\) from the center, the ramp is \(3.20\,\text{m}\) high. a) Find the quadratic function that models the ramp. b) At what horizontal distance from the center is the ramp exactly \(2.00\,\text{m}\) high? Round to the nearest hundredth of a meter.

Hints

- What form does a quadratic have when its vertex is at the origin? - Substitute the given point to find the leading coefficient. - Set the function equal to the requested height and solve for the distance.

Solution

1. Because the vertex is at the origin, use \(f(x) = ax^2\). 2. Substitute the point \((4.00, 3.20)\): \(3.20 = a \cdot 4.00^2 = 16a\), so \(a = 0.2\). Therefore, \(f(x) = 0.2x^2\). 3. Set the height equal to \(2.00\): \(2.00 = 0.2x^2\). Then \(x^2 = 10\), so the two coordinates are \(x = \pm\sqrt{10}\). 4. The requested horizontal distance from the center is positive: \(\sqrt{10}\,\text{m} \approx 3.16\,\text{m}\).

Answer

a) \(f(x) = 0.2x^2\) b) \(\sqrt{10}\,\text{m} \approx 3.16\,\text{m}\) from the center
5287799
The function \(f\) is defined by \(f(x) = 0.5x^2 - 4x + 8\). a) Find the zeros of \(f\). b) Write \(f(x)\) in factored form. c) State the multiplicity of the zero and describe what it means for the graph at that point.

Hints

- Set the function equal to zero to find its zeros. - Look for a perfect-square trinomial after clearing the decimal coefficient. - The exponent on a linear factor gives the multiplicity of its zero. - Decide whether an even-multiplicity zero makes the graph cross or only touch the x-axis.

Solution

1. Set the function equal to zero: \(0.5x^2 - 4x + 8 = 0\). Multiplying both sides by \(2\) gives \(x^2 - 8x + 16 = 0\). 2. Factor the perfect-square trinomial: \((x - 4)^2 = 0\). Therefore, the only zero is \(x = 4\). 3. Including the original leading coefficient, the factored form is \(f(x) = 0.5(x - 4)^2\). 4. The factor \(x - 4\) occurs twice, so the zero has multiplicity 2. The graph touches the x-axis at \((4, 0)\) and does not cross it.

Answer

a) \(x = 4\) b) \(f(x) = 0.5(x - 4)^2\) c) The zero has multiplicity 2. The graph touches the x-axis at \((4, 0)\) without crossing it.
5288569
Let \(h(x)=(x-5)^2+k\), where \(k\) is real. a) For which values of \(k\) does \(h\) have no real zeros? Explain using the vertex. b) Give an example of a downward-opening parabola with exactly two real zeros.

Hints

- In vertex form, \(k\) is the y-coordinate of the vertex. - For an upward-opening parabola, the vertex gives the minimum value. - A downward-opening parabola with a positive maximum crosses the x-axis twice.

Solution

1. The vertex of \(h\) is \((5, k)\), and the parabola opens upward. 2. An upward-opening parabola has no real zeros when its minimum value is positive. Therefore, \(h\) has no real zeros when \(k>0\). 3. A downward-opening parabola has two real zeros when its vertex lies above the x-axis. For example, \(p(x)=-x^2+1\) opens downward and has zeros \(x=-1\) and \(x=1\).

Answer

a) \(k>0\) b) One example is \(p(x)=-x^2+1\).
5333539
Match each graph with its equation. One equation will not be used. (1) \(y = (x + 2)^2\) (2) \(y = (x - 1.5)^2\) (3) \(y = x^2 - 3\) (4) \(y = (x - 4)^2 + 1\) (5) \(y = (x + 3)^2\)
Figure for problem 533353

Hints

- Identify the vertex of each parabola. - In \(y = (x - d)^2 + e\), the vertex is \((d, e)\). - Watch the sign inside the parentheses.

Solution

1. Graph \(f\) has vertex \((-2, 0)\), so it matches (1), \(y = (x + 2)^2\). 2. Graph \(g\) has vertex \((1.5, 0)\), so it matches (2), \(y = (x - 1.5)^2\). 3. Graph \(h\) has vertex \((0, -3)\), so it matches (3), \(y = x^2 - 3\). 4. Graph \(k\) has vertex \((4, 1)\), so it matches (4), \(y = (x - 4)^2 + 1\). 5. Equation (5) would have vertex \((-3, 0)\), which is not shown.

Answer

\(f \rightarrow\) (1) \(g \rightarrow\) (2) \(h \rightarrow\) (3) \(k \rightarrow\) (4) Equation (5) is unused.
5333939
The graphs of quadratic functions \(f\) and \(g\) are shown. a) Write each function in vertex form. b) Estimate the x-intercepts of each function from the graph.
Figure for problem 533393

Hints

- Identify the vertex of each parabola. - Use a point one unit from the vertex to determine the vertical scale factor. - The x-intercepts occur where the graph crosses the x-axis.

Solution

1. The vertex of \(f\) is \((2, -1)\). The parabola has the standard width and opens upward, so \(f(x) = (x - 2)^2 - 1\). 2. The vertex of \(g\) is \((-1, 2)\). Moving one unit right from the vertex lowers the graph by \(0.5\), so \(a = -0.5\). Thus, \(g(x) = -0.5(x + 1)^2 + 2\). 3. From the graph, the x-intercepts of \(f\) are approximately \(1\) and \(3\). The x-intercepts of \(g\) are approximately \(-3\) and \(1\).

Answer

a) \(f(x) = (x - 2)^2 - 1\); \(g(x) = -0.5(x + 1)^2 + 2\) b) \(f\): \(x \approx 1\) and \(x \approx 3\); \(g\): \(x \approx -3\) and \(x \approx 1\)
5333959
Consider \(x^2 - 2x = 3\). a) Rewrite the equation with \(0\) on the right. b) Use the graph of \(f(x) = x^2 - 2x - 3\) to identify the zeros. c) Verify the solutions in the original equation.
Figure for problem 533395

Hints

- Move the constant so one side is \(0\). - Zeros are the x-coordinates where the graph crosses the x-axis. - Substitute each value into the original equation.

Solution

1. Subtract \(3\) from both sides: \(x^2 - 2x - 3 = 0\). 2. The graph crosses the x-axis at \(x = -1\) and \(x = 3\). 3. For \(x = -1\), \((-1)^2 - 2(-1) = 3\). 4. For \(x = 3\), \(3^2 - 2(3) = 3\).

Answer

a) \(x^2 - 2x - 3 = 0\) b) \(x = -1\) and \(x = 3\) c) Both values satisfy the original equation.
5334409
The graph shows the parabolic path of a small fountain stream. Horizontal distance and height above the water surface are measured in meters. a) Which function best matches the graph? Justify your choice using the graph. (1) \(f(x) = -0.25x^2 + 2x\) (2) \(g(x) = -0.5x^2 + 4x\) (3) \(h(x) = 0.25x^2 - 2x\) b) Calculate the maximum height of the stream and compare it with the graph. c) How far from the nozzle does the stream return to the water surface?
Figure for problem 533440

Hints

- Compare the opening direction and a clear point on the graph with each option. - Find the zeros to locate the axis of symmetry. - The positive zero represents where the stream returns to the water surface.

Solution

1. The graph opens downward, so function (3) cannot match. It also passes through \((2, 3)\). For function (1), \(f(2) = -0.25 \cdot 2^2 + 2 \cdot 2 = 3\). Function (2) gives \(g(2) = 6\). Therefore, function (1) matches the graph. 2. Factor \(f(x) = -0.25x(x - 8)\). Its zeros are \(x = 0\) and \(x = 8\), so the vertex lies midway at \(x = 4\). 3. Evaluate \(f(4) = -0.25 \cdot 4^2 + 2 \cdot 4 = 4\). The maximum height is \(4\,\text{m}\), matching the graph. 4. The positive zero \(x = 8\) represents the point where the stream returns to the water surface, so the horizontal range is \(8\,\text{m}\).

Answer

a) Function (1), \(f(x) = -0.25x^2 + 2x\) b) \(4\,\text{m}\) at \(x = 4\) c) \(8\,\text{m}\)
5349089
A ball is launched from a ground-level ramp. The graph shows its path, where horizontal distance and height are measured in feet. 1) What is the ball's height after it has traveled \(1\,\text{ft}\) horizontally? 2) What maximum height does the ball reach, and after what horizontal distance? 3) After what horizontal distance does the ball land?
Figure for problem 534908

Hints

- Read the graph's height at the requested horizontal distance. - The highest point is the vertex. - The landing point is the positive x-intercept.

Solution

1. At \(x = 1\), the graph has height \(y = 3\). The ball is \(3\,\text{ft}\) high. 2. The vertex is \((2, 4)\), so the maximum height is \(4\,\text{ft}\) after a horizontal distance of \(2\,\text{ft}\). 3. The path returns to the x-axis at \((4, 0)\), so the ball lands after \(4\,\text{ft}\).

Answer

1) \(3\,\text{ft}\) 2) A maximum height of \(4\,\text{ft}\) after \(2\,\text{ft}\) horizontally 3) \(4\,\text{ft}\)
5128989
The function \(g\) is defined by \(g(x) = (x+4)^2 - 16\) for all real numbers. a) State the coordinates of the vertex of the parabola. b) Find the y-intercept of the graph of \(g\). c) Without solving an equation, explain how many real zeros \(g\) has. d) Use substitution to determine whether \(x = 2\) is a zero of \(g\).

Hints

- What information can you read directly from vertex form? - What x-value is used to find a y-intercept? - Consider the direction the parabola opens and the location of its vertex relative to the x-axis. - What equation must be true when an x-value is a zero of a function?

Solution

1. The equation is in vertex form \(a(x-h)^2+k\). Here, \(h=-4\) and \(k=-16\), so the vertex is \((-4, -16)\). 2. For the y-intercept, substitute \(x=0\): \(g(0)=(0+4)^2-16=16-16=0\). The y-intercept is \((0, 0)\). 3. The parabola opens upward because \(a=1>0\), and its vertex is below the x-axis. Therefore, the graph crosses the x-axis twice, so \(g\) has two real zeros. 4. Substitute \(x=2\): \(g(2)=(2+4)^2-16=36-16=20\). Since \(g(2)\ne 0\), \(x=2\) is not a zero.

Answer

a) \((-4, -16)\) b) \((0, 0)\) c) Two real zeros; the parabola opens upward and its vertex is below the x-axis. d) No. Since \(g(2)=20\ne 0\), \(x=2\) is not a zero.
5128999
Consider the function \(f(x)=-2(x-1)^2+3\), with domain \(\mathbb{R}\). a) Determine the range of \(f\). b) Determine whether each point lies on, above, or below the graph of \(f\): \(A(0, 2)\) and \(B(2, 0)\). Justify each answer with a calculation.

Hints

- How does the sign of the leading coefficient affect the direction the parabola opens? - Use the vertex to identify the greatest or least possible output. - For each point, compare its y-coordinate with the function value at the same x-coordinate.

Solution

1. The vertex is \((1, 3)\). Because the leading coefficient \(-2\) is negative, the parabola opens downward, so its greatest y-value is \(3\). The range is \((-\infty, 3]\). 2. At \(x=0\), \(f(0)=-2(0-1)^2+3=1\). Point \(A\) has y-coordinate \(2\), and \(2>1\), so \(A\) lies above the graph. 3. At \(x=2\), \(f(2)=-2(2-1)^2+3=1\). Point \(B\) has y-coordinate \(0\), and \(0<1\), so \(B\) lies below the graph.

Answer

a) \((-\infty, 3]\) b) \(A(0, 2)\) lies above the graph because \(f(0)=1<2\). \(B(2, 0)\) lies below the graph because \(f(2)=1>0\).
5129459
The functions are \(h(x) = 2x + 4\) and \(k(x) = (x + 2)(x - 3)\). a) Find all zeros of both functions. b) Explain without drawing why the graphs must intersect on the x-axis. c) A point \(S(1, y_S)\) lies on the graph of \(h\). Find its y-coordinate, and determine whether \(S\) lies above or below the graph of \(k\). d) Find the vertical distance between the graphs at \(x = 0\).

Hints

- Use the linear equation and the factored quadratic form to find zeros. - A shared zero gives a common point on the x-axis. - Compare function values at the same x-coordinate.

Solution

1. For \(h(x) = 0\), \(2x + 4 = 0\), so \(x = -2\). 2. From the factored form of \(k\), its zeros are \(x = -2\) and \(x = 3\). 3. Both functions have value \(0\) at \(x = -2\), so the graphs share the point \((-2, 0)\) on the x-axis. 4. Since \(h(1) = 2 \cdot 1 + 4 = 6\), \(S = (1, 6)\). Also, \(k(1) = 3 \cdot (-2) = -6\), so \(S\) lies above the graph of \(k\). 5. At \(x = 0\), \(h(0) = 4\) and \(k(0) = 2 \cdot (-3) = -6\). The vertical distance is \(|4 - (-6)| = 10\).

Answer

a) \(h\): \(x = -2\); \(k\): \(x = -2\) and \(x = 3\) b) The graphs share \((-2, 0)\). c) \(y_S = 6\), and \(S\) lies above the graph of \(k\). d) \(10\) units
5142769
A parabola has vertex \((-2, 5)\) and passes through the point \((0, 1)\). Find its equation in vertex form. Then rewrite the equation in standard form \(y=ax^2+bx+c\).

Hints

- Which parts of vertex form are determined directly by the vertex? - How can the given point be used to determine \(a\)? - What happens to every term when you distribute a negative sign? - How can you expand the vertex form to obtain standard form?

Solution

1. Substitute the vertex into \(y=a(x-h)^2+k\): \(y=a(x+2)^2+5\). 2. Use the point \((0, 1)\): \(1=a(0+2)^2+5\). 3. Solve for \(a\): \(1=4a+5\), so \(-4=4a\) and \(a=-1\). 4. The vertex form is \(y=-(x+2)^2+5\). 5. Expand the squared binomial: \(y=-(x^2+4x+4)+5\). 6. Combine like terms: \(y=-x^2-4x+1\).

Answer

The vertex form is \(y=-(x+2)^2+5\). The standard form is \(y=-x^2-4x+1\).
5144919
A quadratic function has zeros at \(x = -2\) and \(x = 4\). Its graph passes through \(P(0, -4)\). Find the function in standard form \(f(x) = ax^2 + bx + c\) and state the vertex.

Hints

- Which form is useful when the zeros are known? - How can the additional point determine the leading coefficient? - Where is the axis of symmetry relative to the two zeros? - How do you expand intercept form into standard form?

Solution

1. Write the function in intercept form: \(f(x) = a(x + 2)(x - 4)\). 2. Substitute \(P(0, -4)\): \(-4 = a \cdot 2 \cdot (-4) = -8a\), so \(a = 0.5\). 3. Expand: \(f(x) = 0.5(x + 2)(x - 4) = 0.5x^2 - x - 4\). 4. The axis of symmetry is the midpoint of the zeros: \(x = \frac{-2 + 4}{2} = 1\). 5. Evaluate \(f(1) = 0.5 \cdot 3 \cdot (-3) = -4.5\). Therefore, the vertex is \((1, -4.5)\).

Answer

\(f(x) = 0.5x^2 - x - 4\); vertex \((1, -4.5)\)
5144949
The quadratic function \(f\) is defined by \(f(x)=\frac{1}{2}(x+1)^2-2\). 1. State the vertex of the parabola and determine whether it opens upward or downward. 2. Find the zeros of \(f\). 3. Describe the graph of \(f\), including its axis of symmetry, x-intercepts, and width relative to \(y=x^2\).

Hints

- What information can you read directly from vertex form? - What does the sign of the coefficient outside the squared expression tell you? - What is the y-value at an x-intercept? - How does a coefficient between \(0\) and \(1\) affect the width of a parabola?

Solution

1. The equation is in vertex form \(a(x-h)^2+k\). Here, \(h=-1\) and \(k=-2\), so the vertex is \((-1, -2)\). Since \(a=\frac{1}{2}>0\), the parabola opens upward. 2. Set \(f(x)=0\): \(\frac{1}{2}(x+1)^2-2=0\). 3. Add \(2\) and multiply by \(2\): \((x+1)^2=4\). 4. Take both square roots: \(x+1=2\) or \(x+1=-2\). 5. Therefore, the zeros are \(x=1\) and \(x=-3\). 6. The vertex is \((-1, -2)\), the x-intercepts are \((-3, 0)\) and \((1, 0)\), and the graph is symmetric about \(x=-1\). Since \(0<\frac{1}{2}<1\), the upward-opening parabola is wider than \(y=x^2\).

Answer

1. The vertex is \((-1, -2)\), and the parabola opens upward. 2. The zeros are \(x=-3\) and \(x=1\). 3. The graph is an upward-opening parabola with vertex \((-1, -2)\), axis of symmetry \(x=-1\), and x-intercepts \((-3, 0)\) and \((1, 0)\). It is wider than \(y=x^2\).
5145039
The parent parabola \(y=x^2\) is translated so that its vertex is \((3, -2)\). a) Write the equation of the translated parabola in vertex form and in standard form. b) The domain is restricted to \(x\in[1, 5]\). Determine the range on this restricted domain.

Hints

- How are the vertex coordinates represented in vertex form? - Use the square of a binomial to expand the expression. - Is the vertex included in the restricted domain? - Compare the function values at the vertex and the endpoints of the interval.

Solution

1. A translation of \(y=x^2\) has leading coefficient \(1\). Using the vertex \((3, -2)\), the vertex form is \(f(x)=(x-3)^2-2\). 2. Expand: \(f(x)=x^2-6x+9-2=x^2-6x+7\). 3. The vertex x-coordinate \(3\) lies in \([1, 5]\). Since the parabola opens upward, the minimum value on the interval is \(-2\). 4. Evaluate the endpoints: \(f(1)=(1-3)^2-2=2\) and \(f(5)=(5-3)^2-2=2\). 5. Therefore, the maximum value on the interval is \(2\), and the range is \([-2, 2]\).

Answer

a) Vertex form: \(f(x)=(x-3)^2-2\) Standard form: \(f(x)=x^2-6x+7\) b) \([-2, 2]\)
5145049
The functions \(f(x)=x^2\) and \(g(x)=-(x-2)^2+2\) are given. a) Determine algebraically how many intersection points the graphs have, and give the coordinates of each intersection point. b) Determine the range of \(g\) for \(x\in\mathbb{R}\). Justify your answer using the vertex and the direction the parabola opens.

Hints

- Set the two function expressions equal to find common points. - What does the number of solutions of the resulting equation tell you about the graphs? - How does the sign outside the squared expression affect the direction the parabola opens? - How does the y-coordinate of the vertex determine the range?

Solution

1. At an intersection, the function values are equal: \(x^2=-(x-2)^2+2\). 2. Expand and simplify: \(x^2=-x^2+4x-2\), so \(2x^2-4x+2=0\). 3. Divide by \(2\) and factor: \(x^2-2x+1=0\), so \((x-1)^2=0\). 4. The only solution is \(x=1\). Then \(y=f(1)=1\), so the graphs have one intersection point, \((1, 1)\). 5. The vertex of \(g\) is \((2, 2)\). Because the coefficient of the squared expression is negative, the parabola opens downward. 6. The vertex gives the maximum value \(2\), so the range is \((-\infty, 2]\).

Answer

a) The graphs have exactly one intersection point: \((1, 1)\). b) \((-\infty, 2]\), because \(g\) opens downward and has a maximum value of \(2\) at its vertex.
5145199
The points \(A(2, 1.5)\), \(B(-1, -1.5)\), \(C(0, 4)\), \(D(3, 13)\), and \(E(1, -2)\) lie on three different parabolas of the form \(f(x)=x^2+k\). Determine the three corresponding values of \(k\).

Hints

- Substitute each point's x- and y-coordinates into the equation. - Rearrange the equation so that the parameter is isolated. - Calculate the parameter for each point, then identify repeated values.

Solution

1. For a point \((x, y)\) on the graph, solve \(y=x^2+k\) for the parameter: \(k=y-x^2\). 2. For \(A(2, 1.5)\), \(k=1.5-2^2=-2.5\). 3. For \(B(-1, -1.5)\), \(k=-1.5-(-1)^2=-2.5\). 4. For \(C(0, 4)\), \(k=4-0^2=4\). 5. For \(D(3, 13)\), \(k=13-3^2=4\). 6. For \(E(1, -2)\), \(k=-2-1^2=-3\). 7. The three distinct values are \(-2.5\), \(4\), and \(-3\).

Answer

The three values of \(k\) are \(-2.5\), \(4\), and \(-3\).
5145309
A translation of the parent parabola \(y=x^2\) has its vertex on the y-axis and passes through the point \(P(3, 5)\). 1. Find the equation of the parabola. 2. Find its zeros.

Hints

- What form does a vertical translation of \(y=x^2\) have? - What does it mean for the vertex to lie on the y-axis? - Substitute the coordinates of the given point into the equation. - What function value corresponds to a zero?

Solution

1. A translation of \(y=x^2\) with its vertex on the y-axis has the form \(f(x)=x^2+k\). 2. Substitute \(P(3, 5)\): \(5=3^2+k\), so \(5=9+k\) and \(k=-4\). Therefore, \(f(x)=x^2-4\). 3. To find the zeros, set \(f(x)=0\): \(x^2-4=0\). 4. Then \(x^2=4\), so \(x=-2\) or \(x=2\).

Answer

1. \(f(x)=x^2-4\) 2. The zeros are \(x=-2\) and \(x=2\).
5145389
Two translated parabolas are defined by \(p_1(x)=x^2-4x+4\) and \(p_2(x)=x^2-4x+5\). Find the vertex of each parabola. Then use the vertex locations to explain how many real zeros each function has.

Hints

- Rewrite each equation in vertex form. - Locate each vertex relative to the x-axis and note the direction the parabola opens. - Decide whether each graph crosses, touches, or does not reach the x-axis.

Solution

1. Rewrite \(p_1\): \(x^2-4x+4=(x-2)^2\). Its vertex is \((2, 0)\). 2. The first parabola opens upward and its vertex lies on the x-axis, so it touches the x-axis once. Thus, \(p_1\) has one distinct real zero. 3. Rewrite \(p_2\): \(x^2-4x+5=(x-2)^2+1\). Its vertex is \((2, 1)\). 4. The second parabola opens upward and its minimum value is \(1\), so it never reaches the x-axis. Thus, \(p_2\) has no real zeros.

Answer

For \(p_1\), the vertex is \((2, 0)\), and the function has one distinct real zero. For \(p_2\), the vertex is \((2, 1)\), and the function has no real zeros.
5145419
The family of functions is given by \(f_k(x) = (x - 3)^2 + k\), where \(k\) is a real number. Find all values of \(k\) for which \(f_k(x) = 0\): a) has exactly one real solution. b) has the solutions \(x = 1\) and \(x = 5\). c) has no real solutions. Justify your answer for part c).

Hints

- Identify the vertex from the function’s form. - Relate the vertex’s vertical position to the number of x-intercepts. - For part b), substitute one of the given zeros into the function.

Solution

1. The function is in vertex form, with vertex \((3, k)\), and the parabola opens upward. 2. For exactly one real solution, the vertex must lie on the x-axis, so \(k = 0\). 3. For the solutions \(1\) and \(5\), substitute either value. Using \(x = 1\), \((1 - 3)^2 + k = 0\), so \(4 + k = 0\) and \(k = -4\). Substituting \(x = 5\) gives the same value. 4. Because \((x - 3)^2 \ge 0\), the expression \((x - 3)^2 + k\) is always positive when \(k > 0\). Therefore, there are no real solutions for \(k > 0\).

Answer

a) \(k = 0\) b) \(k = -4\) c) \(k > 0\)
5145479
The functions \(f(x)=x^2-4x+4\) and \(g(x)=x^2+10x+25\) are given. a) Find the vertex of each parabola. b) Describe precisely how to translate the graph of \(f\) so that it coincides with the graph of \(g\).

Hints

- Rewrite each function as the square of a binomial. - Locate the two vertices on the x-axis. - Find the horizontal distance and direction from the vertex of \(f\) to the vertex of \(g\).

Solution

1. Rewrite each perfect-square trinomial: \(f(x)=(x-2)^2\) and \(g(x)=(x+5)^2\). 2. Therefore, the vertices are \((2, 0)\) for \(f\) and \((-5, 0)\) for \(g\). 3. The horizontal change from \(2\) to \(-5\) is \(-5-2=-7\). 4. Translate the graph of \(f\) \(7\) units left to make it coincide with the graph of \(g\).

Answer

a) The vertex of \(f\) is \((2, 0)\), and the vertex of \(g\) is \((-5, 0)\). b) Translate the graph of \(f\) \(7\) units left.
5145489
A quadratic function has the form \(f(x) = (x - h)^2 + k\). Its graph passes through \((-2, 11)\) and \((4, 11)\), and its minimum value is \(2\). Find the vertex and write the complete function equation.

Hints

- What does it tell you when two points on a parabola have the same \(y\)-coordinate? - Which coordinate of the vertex equals the minimum value? - How do you write vertex form once you know the vertex?

Solution

1. The points \((-2, 11)\) and \((4, 11)\) have the same \(y\)-coordinate, so they are symmetric about the axis of symmetry. The axis is halfway between their \(x\)-coordinates: \(x = \frac{-2 + 4}{2} = 1\). 2. The minimum value is the \(y\)-coordinate of the vertex, so \(k = 2\). 3. The vertex is \((1, 2)\), and the function is \(f(x) = (x - 1)^2 + 2\).

Answer

The vertex is \((1, 2)\), and the function is \(f(x) = (x - 1)^2 + 2\).
5145499
The graph of \(g(x) = x^2 + px + q\) passes through \(P(1, 5)\) and \(Q(5, 5)\). a) Use the symmetry of a parabola to explain the \(x\)-coordinate of the vertex. b) Find \(p\) and \(q\).

Hints

- Where is the axis of symmetry when two points on a parabola have the same \(y\)-coordinate? - Once you know the vertex's \(x\)-coordinate, how can you start writing vertex form? - How do you expand vertex form and compare coefficients?

Solution

1. The points have the same \(y\)-coordinate, so the axis of symmetry is halfway between their \(x\)-coordinates: \(x = \frac{1 + 5}{2} = 3\). Therefore, the vertex has \(x\)-coordinate \(3\). 2. Because the leading coefficient is \(1\), write \(g(x) = (x - 3)^2 + k\). Substitute \((5, 5)\): \(5 = (5 - 3)^2 + k\), so \(k = 1\). 3. Expand: \(g(x) = (x - 3)^2 + 1 = x^2 - 6x + 10\). 4. Comparing coefficients with \(x^2 + px + q\) gives \(p = -6\) and \(q = 10\).

Answer

a) The vertex has \(x\)-coordinate \(3\), the midpoint of \(1\) and \(5\). b) \(p = -6\) and \(q = 10\)
5145509
A downward-opening quadratic with leading coefficient \(-1\) has zeros at \(x = -3\) and \(x = 5\). Find the vertex, write the function in vertex form, and state the maximum value.

Hints

- What are the \(y\)-coordinates of the zeros? - How are the zeros related to the axis of symmetry? - What does a leading coefficient of \(-1\) tell you about the form and direction of the parabola?

Solution

1. The axis of symmetry is halfway between the zeros: \(x = \frac{-3 + 5}{2} = 1\). 2. Since the leading coefficient is \(-1\), write \(f(x) = -(x - 1)^2 + k\). 3. Substitute the zero \((5, 0)\): \(0 = -(5 - 1)^2 + k = -16 + k\), so \(k = 16\). 4. Therefore, \(f(x) = -(x - 1)^2 + 16\), the vertex is \((1, 16)\), and the maximum value is \(16\).

Answer

The vertex is \((1, 16)\), the function is \(f(x) = -(x - 1)^2 + 16\), and the maximum value is \(16\).
5145669
Let \(f(x) = x^2 + 6x + 5\). a) Find the vertex of the parabola. b) Find the zeros of \(f\). c) The parabola is shifted \(3\) units left. Write the new function \(g\) in vertex form.

Hints

- Can you rewrite the quadratic in vertex form by completing the square? - Can the quadratic be factored to find its zeros? - How does a horizontal shift change the value inside the squared binomial?

Solution

1. Complete the square: \(f(x) = x^2 + 6x + 9 - 9 + 5 = (x + 3)^2 - 4\). Therefore, the vertex is \((-3, -4)\). 2. Factor the original expression: \(x^2 + 6x + 5 = (x + 1)(x + 5)\). Thus, the zeros are \(x = -1\) and \(x = -5\). 3. Shifting the graph \(3\) units left moves the vertex from \((-3, -4)\) to \((-6, -4)\). Therefore, \(g(x) = (x + 6)^2 - 4\).

Answer

a) \((-3, -4)\) b) \(x = -5\) and \(x = -1\) c) \(g(x) = (x + 6)^2 - 4\)
5145679
Consider \(h(x) = -0.5x^2 + 2x + 6\). a) Rewrite the function in vertex form and state the vertex. b) Find the zeros of the function. c) The graph of \(h\) is reflected across the \(x\)-axis and then shifted \(2\) units up. Find the vertex of the resulting parabola.

Hints

- How does factoring the leading coefficient help you complete the square? - Can you solve for the zeros directly from vertex form? - What happens to a point's coordinates when the graph is reflected across the \(x\)-axis?

Solution

1. Factor \(-0.5\) from the variable terms and complete the square: \(h(x) = -0.5(x^2 - 4x) + 6 = -0.5((x - 2)^2 - 4) + 6 = -0.5(x - 2)^2 + 8\). The vertex is \((2, 8)\). 2. Set the vertex form equal to zero: \(-0.5(x - 2)^2 + 8 = 0\). Then \((x - 2)^2 = 16\), so \(x - 2 = \pm 4\). The zeros are \(x = -2\) and \(x = 6\). 3. Reflecting across the \(x\)-axis changes the vertex to \((2, -8)\). Shifting up \(2\) units changes it to \((2, -6)\).

Answer

a) \(h(x) = -0.5(x - 2)^2 + 8\); vertex \((2, 8)\) b) \(x = -2\) and \(x = 6\) c) \((2, -6)\)
5145949
A parabola must satisfy all three conditions: - Its vertex is \((-2, -4)\). - It opens upward. - It is wider than the parent parabola \(y=x^2\). a) Give one possible equation for the parabola in vertex form. b) Give the range of your function. c) How would the range change if the coefficient \(a\) in your function were multiplied by \(-1\)? Briefly explain.

Hints

- Begin with vertex form using the given vertex. - Which values of \(a\) produce an upward-opening parabola wider than \(y=x^2\)? - Use the vertex and opening direction to determine the range. - What changes when only the sign of \(a\) is reversed?

Solution

1. Using the vertex, write \(g(x)=a(x+2)^2-4\). 2. Opening upward requires \(a>0\), and being wider than \(y=x^2\) requires \(0<a<1\). One possible choice is \(a=0.5\), giving \(g(x)=0.5(x+2)^2-4\). 3. This parabola opens upward and has minimum value \(-4\), so its range is \([-4,\infty)\). 4. Multiplying \(a\) by \(-1\) makes the parabola open downward without changing the vertex. The vertex becomes the maximum, so the new range is \((-\infty,-4]\).

Answer

a) One possible equation is \(g(x)=0.5(x+2)^2-4\). Any value of \(a\) with \(0<a<1\) works. b) \([-4,\infty)\) c) The range becomes \((-\infty,-4]\) because the parabola opens downward and has maximum value \(-4\).
5145959
Consider \(f(x)=0.5(x+2)^2-1\) and \(h(x)=3(x+2)^2-1\). a) Compare the vertices and axes of symmetry of the two graphs. b) On what interval are both functions strictly decreasing? c) Determine whether \(P(0, 1)\) lies on the graph of \(f\), the graph of \(h\), both graphs, or neither graph.

Hints

- Which parts of the two vertex-form equations are the same? - Where does an upward-opening parabola change from decreasing to increasing? - Substitute the point's x-coordinate into each function. - Compare each function value with the point's y-coordinate.

Solution

1. Both equations have vertex form \(a(x-h)^2+k\) with \(h=-2\) and \(k=-1\). Thus, both graphs have vertex \((-2, -1)\) and axis of symmetry \(x=-2\). 2. Both leading coefficients are positive, so both parabolas open upward. An upward-opening parabola is strictly decreasing to the left of and through its vertex. Therefore, both functions are strictly decreasing on \((-\infty,-2]\). 3. Evaluate \(f(0)\): \(f(0)=0.5(0+2)^2-1=0.5\cdot 4-1=1\). Thus, \(P\) lies on the graph of \(f\). 4. Evaluate \(h(0)\): \(h(0)=3(0+2)^2-1=3\cdot 4-1=11\). Since \(11\ne 1\), \(P\) does not lie on the graph of \(h\).

Answer

a) Both graphs have vertex \((-2, -1)\) and axis of symmetry \(x=-2\). b) \((-\infty,-2]\) c) The point \(P(0, 1)\) lies only on the graph of \(f\).
5146169
The function \(h(x) = 0.25(x + 1)(x - 7)\) is given in intercept form. Rewrite \(h\) in vertex form.

Hints

- What can you read directly from intercept form? - Where is the axis of symmetry relative to the two zeros? - Once you know the vertex, how do you write vertex form with the same leading coefficient?

Solution

1. The zeros are \(x = -1\) and \(x = 7\), so the axis of symmetry is their midpoint: \(x = \frac{-1 + 7}{2} = 3\). 2. Evaluate the function at \(x = 3\): \(h(3) = 0.25(3 + 1)(3 - 7) = 0.25 \cdot 4 \cdot (-4) = -4\). The vertex is \((3, -4)\). 3. Keep the leading coefficient \(0.25\) and use the vertex: \(h(x) = 0.25(x - 3)^2 - 4\).

Answer

\(h(x) = 0.25(x - 3)^2 - 4\)
5146319
Consider the quadratic \(y = x^2 - 10x + 21\). 1) Find the vertex. 2) By how many units, and in which direction, must the graph be shifted vertically so that its new vertex lies on the \(x\)-axis?

Hints

- How can you rewrite the quadratic in vertex form? - What is the \(y\)-coordinate of any point on the \(x\)-axis? - How does a vertical shift change the vertex?

Solution

1. Complete the square: \(y = x^2 - 10x + 25 - 25 + 21 = (x - 5)^2 - 4\). 2. The vertex is \((5, -4)\). 3. To move the vertex from \((5, -4)\) to the \(x\)-axis, shift the graph \(4\) units up.

Answer

1) \((5, -4)\) 2) Shift the graph \(4\) units up.
5146469
Consider \(h(x) = -x^2 + 4x - 3\). a) Find the \(x\)-intercepts of the graph. b) Translate the graph so that its vertex is at \((0, 2)\), without changing its opening direction or width. Write the new function in the form \(g(x) = ax^2 + c\).

Hints

- Can you factor the equation used to find the \(x\)-intercepts? - Which coefficient controls the opening direction and width of a parabola? - What does vertex form look like when the vertex lies on the \(y\)-axis?

Solution

1. Set \(h(x) = 0\): \(-x^2 + 4x - 3 = 0\), or \(x^2 - 4x + 3 = 0\). Factoring gives \((x - 1)(x - 3) = 0\), so the \(x\)-intercepts are \((1, 0)\) and \((3, 0)\). 2. The original leading coefficient is \(-1\), so the translated graph must keep leading coefficient \(-1\). 3. A quadratic with vertex \((0, 2)\) and leading coefficient \(-1\) is \(g(x) = -(x - 0)^2 + 2 = -x^2 + 2\).

Answer

a) \((1, 0)\) and \((3, 0)\) b) \(g(x) = -x^2 + 2\)
5146889
Consider the product of three times a number and the number that is \(5\) less than the original number. For what value of the number is the product minimized, and what is the minimum product?

Hints

- Translate the verbal description into a product involving one variable. - Expand the product to obtain a quadratic. - Which feature of an upward-opening parabola gives its minimum?

Solution

1. Let \(x\) be the number. The product is \(P(x) = 3x(x - 5) = 3x^2 - 15x\). 2. Since the leading coefficient is positive, the quadratic has a minimum at its vertex. The vertex occurs at \(x = -\frac{-15}{2 \cdot 3} = 2.5\). 3. Evaluate the product: \(P(2.5) = 3 \cdot 2.5 \cdot (2.5 - 5) = -18.75\).

Answer

The number is \(2.5\), and the minimum product is \(-18.75\).
5146909
The first of two rational numbers is \(10\) greater than the second. Find the two numbers that make their product as small as possible, and find that minimum product.

Hints

- Express the second number in terms of the first. - Write the product as a quadratic function. - Use the vertex to find the minimum.

Solution

1. Let the first number be \(x\). Then the second number is \(x - 10\). 2. Their product is \(P(x) = x(x - 10) = x^2 - 10x\). 3. The parabola opens upward, so its minimum occurs at the vertex: \(x = -\frac{-10}{2} = 5\). 4. The second number is \(5 - 10 = -5\), and the product is \(5 \cdot (-5) = -25\).

Answer

The numbers are \(5\) and \(-5\), and the minimum product is \(-25\).
5146959
The parabola is \(f(x) = x^2 - 4x + 7\). a) Find its vertex. b) A horizontal line has equation \(y = c\). Find all values of \(c\) for which the line and parabola have exactly two intersection points. c) Without further calculation, determine the number of intersections when \(c = 2\).

Hints

- Write the function in vertex form. - Compare the height of the horizontal line with the minimum value. - Use the opening direction of the parabola.

Solution

1. Complete the square: \(f(x) = x^2 - 4x + 4 + 3 = (x - 2)^2 + 3\). The vertex is \((2, 3)\). 2. The parabola opens upward and has minimum value \(3\). 3. A horizontal line intersects it twice exactly when the line lies above the vertex, so \(c > 3\). 4. When \(c = 2\), the line lies below the minimum value, so there are no intersections.

Answer

a) \((2, 3)\) b) \(c > 3\) c) No intersections
5146999
Two real numbers have a sum of \(20\). Choose the numbers so that the sum of their squares is as small as possible. Justify your result by writing and analyzing a function.

Hints

- Express one number in terms of the other using their sum. - Write the sum of squares as a quadratic function. - Use the vertex to find the minimum.

Solution

1. Let the numbers be \(x\) and \(y\). Since \(x + y = 20\), \(y = 20 - x\). 2. The sum of their squares is \(S(x) = x^2 + (20 - x)^2 = 2x^2 - 40x + 400\). 3. This quadratic opens upward, so its minimum occurs at the vertex: \(x = -\frac{-40}{2 \cdot 2} = 10\). 4. Then \(y = 20 - 10 = 10\), and the minimum sum of squares is \(10^2 + 10^2 = 200\).

Answer

The numbers are \(10\) and \(10\), and the minimum sum of their squares is \(200\).
5147089
A parabola crosses the \(x\)-axis at \(x = -1\) and \(x = 3\). It also passes through \(P(1, -4)\). Find the function in standard form \(f(x) = ax^2 + bx + c\).

Hints

- Which form uses the zeros directly? - How can the additional point determine the leading coefficient? - How do you expand a product into standard form?

Solution

1. Use intercept form: \(f(x) = a(x + 1)(x - 3)\). 2. Substitute \(P(1, -4)\): \(-4 = a \cdot 2 \cdot (-2) = -4a\), so \(a = 1\). 3. Expand: \(f(x) = (x + 1)(x - 3) = x^2 - 2x - 3\).

Answer

\(f(x) = x^2 - 2x - 3\)
5152799
Two kangaroo jumps are modeled by \(f(x) = -0.5(x - 2)^2 + 2\) and \(g(x) = -0.2(x - 3)^2 + 1.8\), where \(x\) is horizontal distance from the starting point and each output is height, all in meters. a) Which jump reaches the greater maximum height? Use the vertices to justify your answer. b) Find the horizontal distance of each jump. Assume both jumps begin at \(x = 0\). c) Which jump is flatter? Explain using the functions and your results.

Hints

- Read each maximum directly from vertex form. - Set each function equal to \(0\) to find where the jump begins and ends. - How does the absolute value of the leading coefficient affect the width of a parabola?

Solution

1. The function \(f\) has vertex \((2, 2)\), so its maximum height is \(2\,\text{m}\). The function \(g\) has vertex \((3, 1.8)\), so its maximum height is \(1.8\,\text{m}\). Therefore, the first jump reaches the greater maximum height. 2. For \(f\), solve \(0 = -0.5(x - 2)^2 + 2\). Then \((x - 2)^2 = 4\), so \(x = 0\) or \(x = 4\). The first jump covers \(4\,\text{m}\). 3. For \(g\), solve \(0 = -0.2(x - 3)^2 + 1.8\). Then \((x - 3)^2 = 9\), so \(x = 0\) or \(x = 6\). The second jump covers \(6\,\text{m}\). 4. The second jump is flatter because its leading coefficient has the smaller absolute value: \(|-0.2| < |-0.5|\). It also has a lower maximum height while covering a greater horizontal distance.

Answer

a) The first jump, with a maximum height of \(2\,\text{m}\), compared with \(1.8\,\text{m}\) for the second jump b) First jump: \(4\,\text{m}\) Second jump: \(6\,\text{m}\) c) The second jump is flatter because \(|-0.2| < |-0.5|\); it is wider and has a lower maximum.
5153339
A parabola crosses the \(x\)-axis at \(x = -2\) and \(x = 6\). It also passes through \(P(0, 3)\). Find the vertex of the parabola.

Hints

- Which form of a quadratic is useful when its zeros are known? - Where is the axis of symmetry relative to the two zeros? - How can the given point help you determine the leading coefficient?

Solution

1. Use intercept form: \(f(x) = a(x + 2)(x - 6)\). 2. Substitute \(P(0, 3)\): \(3 = a(0 + 2)(0 - 6) = -12a\), so \(a = -0.25\). 3. The axis of symmetry is halfway between the zeros: \(x = \frac{-2 + 6}{2} = 2\). 4. Evaluate the function at \(x = 2\): \(f(2) = -0.25(2 + 2)(2 - 6) = -0.25 \cdot 4 \cdot (-4) = 4\). 5. Therefore, the vertex is \((2, 4)\).

Answer

The vertex is \((2, 4)\).
5153619
A basketball player shoots a ball. The ball is released from a height of \(6\,\text{ft}\) at \((0, 6)\). Its highest point is \((8, 12)\), where horizontal distance and height are measured in feet. a) Find the path function \(f(x)\) in vertex form. b) Find the ball's height after it has traveled \(12\,\text{ft}\) horizontally. c) If the ball is not caught or stopped, how far horizontally from the release point would it hit the ground? Round to the nearest hundredth of a foot.

Hints

- Use the highest point as the vertex in vertex form. - Substitute the release point to determine the leading coefficient. - Hitting the ground means the height is \(0\).

Solution

1. Use the vertex \((8, 12)\): \(f(x) = a(x - 8)^2 + 12\). 2. Substitute the release point \((0, 6)\): \(6 = a(0 - 8)^2 + 12\). Then \(64a = -6\), so \(a = -\frac{3}{32}\). Thus, \(f(x) = -\frac{3}{32}(x - 8)^2 + 12\). 3. Evaluate at \(x = 12\): \(f(12) = -\frac{3}{32} \cdot (12 - 8)^2 + 12 = 10.5\). The ball is \(10.5\,\text{ft}\) high. 4. Set \(f(x) = 0\): \(0 = -\frac{3}{32}(x - 8)^2 + 12\). Then \((x - 8)^2 = 128\), so \(x = 8 \pm 8\sqrt{2}\). 5. The context-valid positive distance is \(x = 8 + 8\sqrt{2} \approx 19.31\,\text{ft}\).

Answer

a) \(f(x) = -\frac{3}{32}(x - 8)^2 + 12\) b) \(10.5\,\text{ft}\) c) \(8 + 8\sqrt{2}\,\text{ft} \approx 19.31\,\text{ft}\)
5231919
The quadratic function is \(f(x) = x^2 + 6x + 5\). Rewrite \(f\) in vertex form to identify its axis of symmetry. Then verify algebraically that the graph is symmetric about \(x = -3\) by showing that \(f(-3 + h) = f(-3 - h)\) for every real number \(h\).

Hints

- Complete the square to rewrite the quadratic in vertex form. - Substitute \(-3 + h\) and \(-3 - h\) for \(x\). - Expand each squared binomial carefully. - Compare the simplified results.

Solution

1. Complete the square: \(f(x) = x^2 + 6x + 5 = (x + 3)^2 - 4\). Therefore, the axis of symmetry is \(x = -3\). 2. Evaluate the function on one side of the axis: \(f(-3 + h) = (-3 + h)^2 + 6(-3 + h) + 5 = h^2 - 4\). 3. Evaluate the function the same distance on the other side: \(f(-3 - h) = (-3 - h)^2 + 6(-3 - h) + 5 = h^2 - 4\). 4. Since \(f(-3 + h) = f(-3 - h)\) for every real \(h\), the graph is symmetric about \(x = -3\).

Answer

Vertex form: \(f(x) = (x + 3)^2 - 4\) Axis of symmetry: \(x = -3\) The verification gives \(f(-3 + h) = f(-3 - h) = h^2 - 4\).
5232419
Find the parameters \(a\), \(b\), and \(c\) in \(f(x) = a(x - b)(x - c)\) so that the zeros are \(-2\) and \(6\), and the graph passes through \((2, 8)\). Also write the resulting function in standard form \(f(x) = ax^2 + px + q\).

Hints

- Use each zero to write a corresponding linear factor. - Substitute the coordinates of the given point to determine \(a\). - Multiply the binomials and distribute \(a\) to obtain standard form.

Solution

1. Zeros of \(-2\) and \(6\) give the factors \(x + 2\) and \(x - 6\), so \(f(x) = a(x + 2)(x - 6)\). Thus, \(b = -2\) and \(c = 6\), or the two values may be reversed. 2. Use the point \((2, 8)\): \(8 = a(2 + 2)(2 - 6) = a(4)(-4) = -16a\). 3. Solve for the leading coefficient: \(a = -\frac{1}{2}\). 4. The intercept form is \(f(x) = -\frac{1}{2}(x + 2)(x - 6)\). 5. Expand: \((x + 2)(x - 6) = x^2 - 4x - 12\), so \(f(x) = -\frac{1}{2}x^2 + 2x + 6\).

Answer

\(a = -\frac{1}{2}\), with \((b, c) = (-2, 6)\) or \((6, -2)\) Standard form: \(f(x) = -\frac{1}{2}x^2 + 2x + 6\)
5232429
The graph of the quadratic function \(g(x) = a(x - s)(x - t)\) touches the x-axis at \(x = 3\). The point \((5, -10)\) lies on the graph. 1. Find \(a\), \(s\), and \(t\). 2. Find the y-intercept of the graph.

Hints

- When a parabola touches the x-axis at a zero, that zero has multiplicity 2. - A double zero means the two factors \(x - s\) and \(x - t\) are the same. - The y-intercept occurs where \(x = 0\).

Solution

1. Because the graph touches the x-axis at \(x = 3\), \(x = 3\) is a double zero. Therefore, \(s = t = 3\), and \(g(x) = a(x - 3)^2\). 2. Substitute the point \((5, -10)\): \(-10 = a(5 - 3)^2 = 4a\). Thus, \(a = -\frac{5}{2}\). 3. To find the y-intercept, evaluate \(g(0)\): \(g(0) = -\frac{5}{2}(0 - 3)^2 = -\frac{5}{2}(9) = -\frac{45}{2}\). 4. The y-intercept is \((0, -22.5)\).

Answer

1. \(a = -\frac{5}{2}\), \(s = 3\), and \(t = 3\) 2. \((0, -22.5)\)
5254269
Let \(h(x) = -x^2 + 10x - 25\). a) Find the vertex and state whether the parabola opens upward or downward. b) Find the \(y\)-intercept. c) Explain without graphing why the function cannot have any positive output values.

Hints

- Can you factor a negative sign from the entire expression? - What does the leading coefficient tell you about the opening direction? - What is the \(x\)-coordinate of a point on the \(y\)-axis? - What do you know about the value of a square?

Solution

1. Factor out \(-1\): \(h(x) = -(x^2 - 10x + 25) = -(x - 5)^2\). The vertex is \((5, 0)\), and the negative leading coefficient means the parabola opens downward. 2. Evaluate at \(x = 0\): \(h(0) = -25\), so the \(y\)-intercept is \((0, -25)\). 3. For every real \(x\), \((x - 5)^2 \geq 0\). Therefore, \(-(x - 5)^2 \leq 0\), so \(h(x)\) can never be positive.

Answer

a) Vertex \((5, 0)\); the parabola opens downward. b) \((0, -25)\) c) Since \(h(x) = -(x - 5)^2\) and every square is nonnegative, \(h(x) \leq 0\) for all real \(x\).
5254769
The quadratic function \(f(x) = x^2 - 6x + 5\) is given. 1. Rewrite the function in vertex form and state the vertex. 2. Use the vertex and the direction in which the parabola opens to explain why \(f(x) = 0\) has exactly two real solutions. 3. Use the vertex form to identify the x-intercepts.

Hints

- Complete the square to rewrite the function in vertex form. - Compare the vertex's y-coordinate with \(0\). - The solutions of \(f(x) = 0\) are the x-coordinates of the x-intercepts.

Solution

1. Complete the square: \(f(x) = x^2 - 6x + 5 = (x - 3)^2 - 4\). The vertex is \((3, -4)\). 2. The leading coefficient is positive, so the parabola opens upward. Its minimum value is \(-4\), which is below the x-axis, so the graph crosses the x-axis twice. 3. Set \((x - 3)^2 - 4 = 0\): \((x - 3)^2 = 4\), so \(x = 1\) or \(x = 5\). The x-intercepts are \((1, 0)\) and \((5, 0)\).

Answer

1. Vertex form: \(f(x) = (x - 3)^2 - 4\); vertex: \((3, -4)\) 2. The parabola opens upward and its vertex is below the x-axis, so it has two x-intercepts. 3. The x-intercepts are \((1, 0)\) and \((5, 0)\).
5256469
The parabola is \(p(x) = -x^2 + 4x\), and a horizontal line is \(y = c\). a) Find the value of \(c\) for which the line is tangent to the parabola. b) Give the point of tangency. c) Without further calculation, determine the number of intersections when \(c = 5\).

Hints

- Find the vertex of the parabola. - A horizontal tangent passes through the vertex. - Compare \(c = 5\) with the maximum function value.

Solution

1. Write the parabola in vertex form: \(p(x) = -(x^2 - 4x) = -(x - 2)^2 + 4\). 2. The vertex is \((2, 4)\), and the parabola opens downward. 3. A horizontal tangent occurs at the vertex, so \(c = 4\), and the point of tangency is \((2, 4)\). 4. The maximum value of the parabola is \(4\). Therefore, the line \(y = 5\) lies above the entire parabola and has no intersection points.

Answer

a) \(c = 4\) b) \((2, 4)\) c) No intersections
5264779
A family of parabolas with leading coefficient \(1\) has vertices that lie on the graph of \(g(x)=x^2-6\). a) Write the family \(f_k\) in vertex form. b) Find the values of \(k\) for which the corresponding parabola has exactly one x-intercept.

Hints

- Use the x-coordinate \(k\) in the given vertex-locus function. - Recall the vertex form \(y=(x-h)^2+v\). - A parabola with one x-intercept is tangent to the x-axis at its vertex.

Solution

1. If the x-coordinate of the vertex is \(k\), then its y-coordinate is \(g(k)=k^2-6\). Thus, the vertex is \((k, k^2-6)\). 2. A parabola with leading coefficient \(1\) and vertex \((h, v)\) has equation \(y=(x-h)^2+v\). Therefore, \(f_k(x)=(x-k)^2+k^2-6\). 3. The parabola has exactly one x-intercept when its vertex lies on the x-axis. Hence, \(k^2-6=0\), so \(k=\pm\sqrt6\).

Answer

a) \(f_k(x)=(x-k)^2+k^2-6\) b) \(k=\sqrt6\) or \(k=-\sqrt6\)
5265119
Let \(f(x) = 2x^2 - 8x + 6\). a) Find the vertex. b) Find the \(x\)-intercepts and the \(y\)-intercept. c) Compare the parabola's opening direction and width with \(y = x^2\).

Hints

- How can you find the vertex of a quadratic in standard form? - What value of \(x\) gives the \(y\)-intercept? - What equation gives the \(x\)-intercepts? - What does the leading coefficient tell you about the graph?

Solution

1. The vertex has \(x\)-coordinate \(x = -\frac{-8}{2 \cdot 2} = 2\). Then \(f(2) = 2 \cdot 2^2 - 8 \cdot 2 + 6 = -2\), so the vertex is \((2, -2)\). 2. The \(y\)-intercept is \((0, f(0)) = (0, 6)\). 3. For the \(x\)-intercepts, solve \(2x^2 - 8x + 6 = 0\). Divide by \(2\): \(x^2 - 4x + 3 = 0\). Factoring gives \((x - 1)(x - 3) = 0\), so the intercepts are \((1, 0)\) and \((3, 0)\). 4. Since the leading coefficient is positive, the parabola opens upward. Since \(|2| > 1\), it is narrower than \(y = x^2\).

Answer

a) \((2, -2)\) b) \(x\)-intercepts: \((1, 0)\) and \((3, 0)\); \(y\)-intercept: \((0, 6)\) c) It opens upward and is narrower than \(y = x^2\).
5265129
Consider the parabolas \(p_1(x) = (x + 2)^2 - 1\) and \(p_2(x) = -0.5x^2 + 2x - 2\). a) Find the vertex of each parabola. b) Without fully calculating the zeros, determine which parabola has more \(x\)-intercepts. Explain. c) Find the \(y\)-intercept of \(p_1\).

Hints

- Which form lets you read a vertex directly? - Use the vertex's position and the opening direction to reason about \(x\)-intercepts. - How many intercepts occur when the vertex lies exactly on the \(x\)-axis? - What input gives the \(y\)-intercept?

Solution

1. From vertex form, \(p_1\) has vertex \((-2, -1)\). 2. Rewrite \(p_2\): \(p_2(x) = -0.5(x^2 - 4x + 4) = -0.5(x - 2)^2\). Its vertex is \((2, 0)\). 3. The graph of \(p_1\) opens upward and has its vertex below the \(x\)-axis, so it crosses the \(x\)-axis twice. The graph of \(p_2\) has its vertex on the \(x\)-axis, so it touches the axis once. Therefore, \(p_1\) has more \(x\)-intercepts. 4. Evaluate \(p_1(0) = (0 + 2)^2 - 1 = 3\), so the \(y\)-intercept is \((0, 3)\).

Answer

a) \(p_1\): \((-2, -1)\); \(p_2\): \((2, 0)\) b) \(p_1\) has two \(x\)-intercepts, while \(p_2\) has one, so \(p_1\) has more. c) \((0, 3)\)
5270189
Consider the parabolas \(p_1: y = x^2 - 4x + 3\) and \(p_2: y = -x^2 + 4x - 1\). 1) Find the vertex of each parabola. 2) Find the intersection points of the two parabolas. 3) Compare their opening directions and widths. What do you notice?

Hints

- Can you rewrite each function in vertex form? - What equation must an intersection point satisfy for both functions? - After finding each \(x\)-coordinate, how do you find the corresponding \(y\)-coordinate? - What does the leading coefficient tell you about opening and width?

Solution

1. Rewrite the functions: \(p_1(x) = (x - 2)^2 - 1\), so its vertex is \((2, -1)\). Also, \(p_2(x) = -(x - 2)^2 + 3\), so its vertex is \((2, 3)\). 2. Set the equations equal: \(x^2 - 4x + 3 = -x^2 + 4x - 1\). This simplifies to \(x^2 - 4x + 2 = 0\), so \(x = 2 \pm \sqrt{2}\). 3. Substituting either value into \(p_1(x) = (x - 2)^2 - 1\) gives \(y = 1\). The intersections are \((2 - \sqrt{2}, 1)\) and \((2 + \sqrt{2}, 1)\). 4. Both leading coefficients have absolute value \(1\), so the parabolas have the same width as \(y = x^2\). The first opens upward, and the second opens downward.

Answer

1) \((2, -1)\) and \((2, 3)\) 2) \((2 - \sqrt{2}, 1)\) and \((2 + \sqrt{2}, 1)\) 3) They have the same width; \(p_1\) opens upward and \(p_2\) opens downward.
5287809
A quadratic function \(g\) has zeros \(x = -1\) and \(x = 3\). Its graph also passes through the point \(P(2, -6)\). a) Write an equation for \(g\) in factored form. b) Expand the equation and write \(g(x)\) in standard form \(ax^2 + bx + c\).

Hints

- Which form of a quadratic function uses its zeros directly? - Substitute the coordinates of the given point to determine the leading coefficient. - Use the distributive property to expand the product of two binomials.

Solution

1. Use the zeros to write \(g(x) = a(x + 1)(x - 3)\). 2. Substitute the point \(P(2, -6)\): \(-6 = a(2 + 1)(2 - 3) = a \cdot 3 \cdot (-1) = -3a\). Therefore, \(a = 2\). 3. The factored form is \(g(x) = 2(x + 1)(x - 3)\). 4. Expand the factors: \((x + 1)(x - 3) = x^2 - 2x - 3\). 5. Multiply by \(2\): \(g(x) = 2x^2 - 4x - 6\).

Answer

a) \(g(x) = 2(x + 1)(x - 3)\) b) \(g(x) = 2x^2 - 4x - 6\)
5288459
A quadratic function has the general form \(f(x)=ax^2+bx+c\). Explain what condition \(a\) must satisfy and how \(a\) affects the parabola. Then find the zeros of \(f(x)=\frac{1}{2}x^2-2x-6\).

Hints

- Consider what happens if the coefficient of \(x^2\) equals zero. - The sign of \(a\) determines whether the graph opens upward or downward. - Clear the fraction before solving the quadratic equation.

Solution

1. A quadratic function requires \(a\ne0\); otherwise, the squared term disappears. If \(a>0\), the parabola opens upward, and if \(a<0\), it opens downward. Larger values of \(|a|\) make the parabola narrower, while values \(0<|a|<1\) make it wider. 2. Set the function equal to zero: \(\frac{1}{2}x^2-2x-6=0\). Multiply by \(2\) to get \(x^2-4x-12=0\). 3. Factor: \((x-6)(x+2)=0\). Therefore, the zeros are \(x=-2\) and \(x=6\).

Answer

\(a\ne0\). Its sign determines the opening direction, and \(|a|\) affects the width. The zeros are \(x=-2\) and \(x=6\).
5288469
Let \(g(x)=-2(x-3)^2+18\). 1. Name the form of the equation and state the vertex. 2. Rewrite the equation in standard form \(ax^2+bx+c\). 3. Find the zeros.

Hints

- In \(a(x-h)^2+k\), the vertex is \((h, k)\). - Expand the square and combine like terms. - After setting the function equal to zero, look for a common factor.

Solution

1. The equation is in vertex form \(a(x-h)^2+k\), so the vertex is \((3, 18)\). 2. Expand: \(g(x)=-2(x^2-6x+9)+18=-2x^2+12x\). 3. Set \(g(x)=0\): \(-2x^2+12x=-2x(x-6)=0\). The zeros are \(x=0\) and \(x=6\).

Answer

1. Vertex form; vertex \((3, 18)\) 2. \(g(x)=-2x^2+12x\) 3. \(x=0\) and \(x=6\)
5288559
Let \(f(x)=2x^2+12x+14\). a) Find the zeros exactly without a calculator. b) Find the vertex. Then write an equation for another parabola \(g\) with the same vertex as \(f\) but no real zeros. Explain why your example works.

Hints

- Simplify the quadratic equation before solving. - The axis of symmetry is halfway between the zeros. - Use vertex form to construct a parabola with the same vertex. - To avoid real zeros, keep the entire graph on one side of the x-axis.

Solution

1. Set \(f(x)=0\) and divide by \(2\): \(x^2+6x+7=0\). 2. Complete the square or use the quadratic formula: \(x=-3\pm\sqrt{2}\). These are the zeros. 3. The axis of symmetry is midway between the zeros, so \(x=-3\). Evaluate \(f(-3)=18-36+14=-4\). The vertex is \((-3, -4)\). 4. One example is \(g(x)=-(x+3)^2-4\). It has the same vertex and opens downward. Its maximum value is \(-4\), so its graph stays below the x-axis and has no real zeros.

Answer

a) \(x=-3-\sqrt{2}\) and \(x=-3+\sqrt{2}\) b) Vertex: \((-3, -4)\). One example is \(g(x)=-(x+3)^2-4\).
5294399
Consider the family \(f_a(x)=x^2-2ax+3a\), where \(a\in\mathbb{R}\). a) Find the vertex in terms of \(a\). b) Find the equation of the locus containing all vertices. c) For which values of \(a\) is the vertex above the x-axis?

Hints

- Complete the square to identify the vertex. - Replace the parameter with the vertex x-coordinate. - Solve the inequality for the vertex y-coordinate.

Solution

1. Complete the square: \(f_a(x)=(x-a)^2-a^2+3a\). Therefore, the vertex is \((a, -a^2+3a)\). 2. Since the vertex x-coordinate is \(x=a\), the locus is \(y=-x^2+3x\). 3. The vertex is above the x-axis when \(-a^2+3a>0\), or \(a(3-a)>0\). This holds for \(0<a<3\).

Answer

a) \((a, -a^2+3a)\) b) \(y=-x^2+3x\) c) \(0<a<3\)
5294409
Consider the family \(g_k(x)=-x^2+2kx-4k\), where \(k\in\mathbb{R}\). a) Find the vertex. b) Show that all vertices lie on the parabola \(y=x^2-4x\). c) Find all values of \(k\) for which the vertex lies below the line \(y=-3\).

Hints

- Complete the square to identify the vertex. - Replace \(k\) with the vertex x-coordinate for the locus. - Factor the quadratic inequality.

Solution

1. Complete the square: \(g_k(x)=-(x-k)^2+k^2-4k\). Therefore, the vertex is \((k, k^2-4k)\). 2. Since the vertex x-coordinate is \(x=k\), its y-coordinate is \(y=x^2-4x\), proving the locus. 3. The vertex lies below \(y=-3\) when \(k^2-4k<-3\), or \((k-1)(k-3)<0\). Thus \(1<k<3\).

Answer

a) \((k, k^2-4k)\) b) \(y=x^2-4x\) c) \(1<k<3\)
5322439
The graph shows two parabolic fountain streams. The function \(f\) models one stream, and \(g\) models the other. Horizontal distance and height are measured in meters. a) Read the vertex of each parabola from the graph. b) Find each function in vertex form. c) Find the intersection point of the two streams in the physical domain shown.
Figure for problem 532243

Hints

- Identify the highest point of each curve. - Substitute a clearly readable ground-level point into vertex form to find the leading coefficient. - At an intersection, the two functions have equal outputs. - Keep only solutions that lie in the physical domain shown.

Solution

1. From the graph, the vertices are \((2, 4)\) for \(f\) and \((3, 3)\) for \(g\). 2. Write \(f(x) = a(x - 2)^2 + 4\). The graph shows that \((0, 0)\) lies on \(f\), so \(0 = 4a + 4\), giving \(a = -1\). Thus, \(f(x) = -(x - 2)^2 + 4\). 3. Write \(g(x) = a(x - 3)^2 + 3\). The graph shows that \((1, 0)\) lies on \(g\), so \(0 = 4a + 3\), giving \(a = -0.75\). Thus, \(g(x) = -0.75(x - 3)^2 + 3\). 4. Set the functions equal: \(-(x - 2)^2 + 4 = -0.75(x - 3)^2 + 3\). Simplifying gives \(x^2 + 2x - 15 = 0\), or \((x - 3)(x + 5) = 0\). 5. The solutions are \(x = 3\) and \(x = -5\). Only \(x = 3\) lies in the physical domain shown. Since \(f(3) = 3\), the intersection point is \((3, 3)\).

Answer

a) \(f\): \((2, 4)\) \(g\): \((3, 3)\) b) \(f(x) = -(x - 2)^2 + 4\) \(g(x) = -0.75(x - 3)^2 + 3\) c) \((3, 3)\)
5322679
The graph shows the path of a basketball, where \(x\) is horizontal distance from the release point and \(f(x)\) is height, both in feet. A \(10\)-foot hoop is located \(16\,\text{ft}\) horizontally from the release point. a) Read the vertex and release height from the graph, and find \(f(x)\) in vertex form. b) Determine whether the ball passes exactly through the hoop. c) If the ball is not caught, find the horizontal distance from the release point where it reaches the ground. Round to the nearest hundredth of a foot.
Figure for problem 532267

Hints

- Read the highest point and the y-intercept from the graph. - Substitute the release point into vertex form to find the leading coefficient. - Test the hoop by evaluating the function at its horizontal position. - Reaching the ground means the height is \(0\).

Solution

1. The graph shows vertex \((12, 10.5)\) and release point \((0, 6)\). Begin with \(f(x) = a(x - 12)^2 + 10.5\). 2. Substitute \((0, 6)\): \(6 = a(0 - 12)^2 + 10.5\). Then \(144a = -4.5\), so \(a = -0.03125 = -\frac{1}{32}\). Therefore, \(f(x) = -\frac{1}{32}(x - 12)^2 + 10.5\). 3. Evaluate the height at the hoop: \(f(16) = -\frac{1}{32} \cdot (16 - 12)^2 + 10.5 = 10\). The ball passes exactly through the hoop. 4. Set the height equal to \(0\): \(0 = -\frac{1}{32}(x - 12)^2 + 10.5\). Then \((x - 12)^2 = 336\), so \(x = 12 \pm 4\sqrt{21}\). 5. The context-valid solution is \(x = 12 + 4\sqrt{21} \approx 30.33\,\text{ft}\).

Answer

a) Vertex: \((12, 10.5)\); release height: \(6\,\text{ft}\) \(f(x) = -\frac{1}{32}(x - 12)^2 + 10.5\) b) Yes. \(f(16) = 10\,\text{ft}\). c) \(12 + 4\sqrt{21}\,\text{ft} \approx 30.33\,\text{ft}\)
5325829
Consider the quadratic family \(f_k(x)=kx^2-(4k+1)x+3k+3\), where \(k\in\mathbb{R}\setminus\{0\}\). Four graphs from the family are labeled p, q, r, and s in the figure. a) Show algebraically that every graph passes through two common points \(A\) and \(B\), and give their coordinates. b) Find the value of \(k\) for the graph that passes through \(C(2, -2)\). c) One displayed graph has its vertex at \(x=2.5\). Find the corresponding value of \(k\) and identify the graph label.
Figure for problem 532582

Hints

- Isolate the factor multiplied by \(k\). - Substitute the coordinates of \(C\) into the function. - Use the formula for the x-coordinate of a parabola’s vertex. - Match the resulting function to a labeled graph.

Solution

1. Rewrite the function as \(f_k(x)=k(x^2-4x+3)-x+3\). The value is independent of \(k\) when \(x^2-4x+3=(x-1)(x-3)=0\). Therefore, the common points are \(A(1, 2)\) and \(B(3, 0)\). 2. Evaluate at \(x=2\): \(f_k(2)=1-k\). Setting \(1-k=-2\) gives \(k=3\). 3. The vertex x-coordinate is \(x_v=\frac{4k+1}{2k}=2+\frac{1}{2k}\). Setting this equal to \(2.5\) gives \(k=1\). The graph for \(k=1\) is \(y=x^2-5x+6\), which is labeled q.

Answer

a) \(A(1, 2)\) and \(B(3, 0)\) b) \(k=3\) c) \(k=1\); graph q
5325979
The figure shows several parabolas from a family \(f_k\), where \(k\in\mathbb{R}\setminus\{0\}\). Each curve is labeled with its value of \(k\), and its vertex is marked. a) Determine an equation for the family \(f_k(x)\), and explain how the graph supports your equation. b) Find the vertex in terms of \(k\). c) Find the equation of the locus containing all vertices, including the attainable x-values.
Figure for problem 532597

Hints

- Use the two x-intercepts to write a factored quadratic. - Use one labeled graph to determine the leading coefficient. - The vertex lies midway between the zeros. - Eliminate \(k\) and keep its restriction.

Solution

1. Each parabola opens downward and has zeros at \(x=0\) and \(x=k\). Thus it has the form \(f_k(x)=c x(x-k)\). 2. The graph for \(k=2\) has vertex \((1, 1)\). Substitution gives \(1=c(1)(1-2)\), so \(c=-1\). Therefore, \(f_k(x)=-x^2+kx\). 3. The vertex lies midway between the zeros, so \(x=\frac{k}{2}\). Its y-coordinate is \(f_k\left(\frac{k}{2}\right)=\frac{k^2}{4}\). Thus the vertex is \(\left(\frac{k}{2}, \frac{k^2}{4}\right)\). 4. Since \(k=2x\), the vertex y-coordinate becomes \(y=x^2\). Because \(k\neq0\), the attainable x-values satisfy \(x\neq0\).

Answer

a) \(f_k(x)=-x^2+kx\) b) \(\left(\frac{k}{2}, \frac{k^2}{4}\right)\) c) \(y=x^2\) for \(x\neq0\)
5333669
Use the clearly visible x-intercepts to write the equation of the monic quadratic in standard form \(f(x) = x^2 + px + q\).
Figure for problem 533366

Hints

- Read both x-intercepts from the graph. - Write the factors \((x - x_1)(x - x_2)\). - Expand and combine like terms.

Solution

1. The graph crosses the x-axis at \(x_1 = -2\) and \(x_2 = 1\). 2. Because the quadratic is monic, its factored form is \(f(x) = (x - x_1)(x - x_2) = (x + 2)(x - 1)\). 3. Expanding gives \(f(x) = x^2 - x + 2x - 2 = x^2 + x - 2\).

Answer

\(f(x) = x^2 + x - 2\)
5333989
The graph of \(g(x) = (x + 1)^2 - 3\) is shown. a) Estimate the zeros from the graph. b) Calculate the zeros exactly and give decimal approximations rounded to the nearest hundredth.
Figure for problem 533398

Hints

- Estimate where the graph crosses the x-axis. - Set the function equal to \(0\) for exact values. - Use both square roots, then evaluate the radicals with a calculator.

Solution

1. From the graph, the zeros are approximately \(x \approx -2.7\) and \(x \approx 0.7\). 2. Set the function equal to zero: \((x + 1)^2 - 3 = 0\). 3. Then \((x + 1)^2 = 3\), so \(x + 1 = \pm\sqrt{3}\). 4. Therefore, \(x = -1 + \sqrt{3}\) or \(x = -1 - \sqrt{3}\). 5. Rounded to the nearest hundredth, the values are \(0.73\) and \(-2.73\).

Answer

a) Approximately \(x = -2.7\) and \(x = 0.7\) b) \(x = -1 - \sqrt{3} \approx -2.73\) and \(x = -1 + \sqrt{3} \approx 0.73\)
5334029
The graph shows a parabolic cross section of a small tunnel. Each coordinate unit represents one meter, and the roadway lies on the x-axis. a) Read the zeros and vertex from the graph. What is the tunnel's width at ground level? b) Find the function in the form \(y = ax^2 + c\). c) A vehicle is \(2\,\text{m}\) wide and travels through the center of the tunnel. What is the greatest possible height of the vehicle if its top corners must not extend above the tunnel?
Figure for problem 533402

Hints

- Interpret the x-intercepts as the points where the tunnel meets the roadway. - The constant term in \(y = ax^2 + c\) is the height at \(x = 0\). - A centered vehicle extends half its width to each side of the y-axis.

Solution

1. From the graph, the zeros are \(x = -2\) and \(x = 2\), and the vertex is \((0, 4)\). The ground-level width is \(2 - (-2) = 4\,\text{m}\). 2. In \(y = ax^2 + c\), the vertex \((0, 4)\) gives \(c = 4\). Using the zero \((2, 0)\), \(0 = a \cdot 2^2 + 4\), so \(4a = -4\) and \(a = -1\). Thus, \(h(x) = -x^2 + 4\). 3. A centered \(2\,\text{m}\)-wide vehicle extends from \(x = -1\) to \(x = 1\). The critical clearance is at its outer top corners: \(h(1) = -1^2 + 4 = 3\). The vehicle can be at most \(3\,\text{m}\) high.

Answer

a) Zeros: \(x = -2\) and \(x = 2\); vertex: \((0, 4)\); width: \(4\,\text{m}\) b) \(h(x) = -x^2 + 4\) c) \(3\,\text{m}\)
5334339
A quadratic function \(h\) passes through \(A(-2, 2)\), \(B(0, 1)\), and \(C(2, 2)\). a) Use the positions of the points to determine the sign of the discriminant of \(h(x) = 0\). Explain your answer. b) By how much must the y-coordinate of \(B\) be decreased to make the discriminant positive?
Figure for problem 533433

Hints

- Use symmetry to identify the vertex. - Determine the opening direction from the three points. - Decide where the vertex must be for two x-intercepts.

Solution

1. Points \(A\) and \(C\) are symmetric about the y-axis and have the same y-coordinate, so \(B(0, 1)\) is the vertex. 2. The parabola opens upward and its vertex lies above the x-axis. Therefore, it has no real zeros and \(D < 0\). 3. To make \(D > 0\), the vertex must lie below the x-axis. The y-coordinate of \(B\) must be decreased from \(1\) to a value less than \(0\). 4. Therefore, it must be decreased by more than \(1\).

Answer

a) \(D < 0\) b) The y-coordinate must be decreased by more than \(1\).
5334359
The graph shows a parabola \(f\). a) Write the equation of \(f\) in vertex form. b) Find the zeros exactly.
Figure for problem 533435

Hints

- Read the vertex from the graph. - Use another labeled point to determine \(a\). - Set the vertex-form expression equal to \(0\) to find the zeros.

Solution

1. The graph shows the vertex \((-2, -4.5)\) and the point \((1, 0)\). 2. Write \(f(x) = a(x + 2)^2 - 4.5\). 3. Substitute \((1, 0)\): \(0 = a(1 + 2)^2 - 4.5\), so \(9a = 4.5\) and \(a = 0.5\). 4. Therefore, \(f(x) = 0.5(x + 2)^2 - 4.5\). 5. Set \(f(x) = 0\): \(0.5(x + 2)^2 = 4.5\), so \((x + 2)^2 = 9\). 6. Thus, \(x + 2 = \pm 3\), giving \(x = 1\) or \(x = -5\).

Answer

a) \(f(x) = 0.5(x + 2)^2 - 4.5\) b) \(x = -5\) and \(x = 1\)
5334539
The graphs of two parabolas \(f\) and \(g\) are shown. a) Determine the equations of \(f\) and \(g\). b) Calculate the exact coordinates of their intersection points.
Figure for problem 533453

Hints

- Read each vertex and one additional point from the graph. - Use vertex form to determine the leading coefficient. - Set the two function rules equal and factor the resulting equation.

Solution

1. The downward-opening parabola \(f\) has vertex \((0, 5)\) and passes through \((1, 4)\). Thus, \(f(x) = ax^2 + 5\), and \(4 = a + 5\), so \(a = -1\). Therefore, \(f(x) = -x^2 + 5\). 2. The upward-opening parabola \(g\) has vertex \((2, 1)\) and passes through \((1, 2)\). Thus, \(g(x) = a(x - 2)^2 + 1\), and \(2 = a + 1\), so \(a = 1\). Therefore, \(g(x) = (x - 2)^2 + 1\). 3. Set the functions equal: \(-x^2 + 5 = (x - 2)^2 + 1\). 4. Simplify: \(2x^2 - 4x = 0\), so \(2x(x - 2) = 0\). Thus, \(x = 0\) or \(x = 2\). 5. The corresponding y-values are \(5\) and \(1\), giving the intersection points \((0, 5)\) and \((2, 1)\).

Answer

a) \(f(x) = -x^2 + 5\) and \(g(x) = (x - 2)^2 + 1\) b) \((0, 5)\) and \((2, 1)\)
5343709
A family of parabolas has vertex form \(f_a(x)=-0.5(x-a)^2+c_a\). Every vertex lies on the parabola \(y=0.25x^2\). a) Find \(f_a(x)\) in terms of \(a\). b) Find the value of \(a\) for which the graph passes through \(P(2, 2)\).

Hints

- Use the vertex coordinates in the given locus equation. - Substitute the given point into the family equation. - Expand carefully using the binomial formula.

Solution

1. The vertex is \((a, c_a)\). Since it lies on \(y=0.25x^2\), \(c_a=0.25a^2\). 2. Therefore, \(f_a(x)=-0.5(x-a)^2+0.25a^2\). 3. Substitute \(P(2, 2)\): \(2=-0.5(2-a)^2+0.25a^2\). 4. Simplifying gives \(a^2-8a+16=0\), or \((a-4)^2=0\). Thus \(a=4\).

Answer

a) \(f_a(x)=-0.5(x-a)^2+0.25a^2\) b) \(a=4\)
5343759
Consider the family \(f_k(x)=x^2-2kx+2k+3\), where \(k\in\mathbb{R}\). Several graphs and the common point \(P\) are shown in the figure. a) Show algebraically that every graph passes through \(P(1, 4)\). b) Find the vertex in terms of \(k\). c) Find the equation of the locus containing all vertices. d) For which values of \(k\) does the graph have no real zeros? e) For which values of \(k\) is the parabola tangent to the x-axis?
Figure for problem 534375

Hints

- Isolate the term containing \(k\). - Complete the square to identify the vertex. - Replace \(k\) with the vertex x-coordinate. - Use the discriminant to determine the number of real zeros.

Solution

1. Rewrite the function as \(f_k(x)=x^2+3-2k(x-1)\). At \(x=1\), the parameter term is zero, so \(f_k(1)=4\). 2. Complete the square: \(f_k(x)=(x-k)^2-k^2+2k+3\). Therefore, the vertex is \((k, -k^2+2k+3)\). 3. Since the vertex x-coordinate is \(x=k\), the locus is \(y=-x^2+2x+3\). 4. The discriminant of \(x^2-2kx+2k+3=0\) is \(4(k-3)(k+1)\). There are no real zeros when the discriminant is negative, so \(-1<k<3\). 5. The parabola is tangent to the x-axis when the discriminant is zero, giving \(k=-1\) or \(k=3\).

Answer

a) \(P(1, 4)\) b) \((k, -k^2+2k+3)\) c) \(y=-x^2+2x+3\) d) \(-1<k<3\) e) \(k=-1\) or \(k=3\)
5348779
A triangular glass panel is bounded by the x-axis, the y-axis, and the line \(g\) with equation \(y = -0.75x + 6\), where lengths are measured in feet. A rectangular solar panel with sides parallel to the coordinate axes is placed inside the triangle with one vertex at the origin and the opposite vertex \(P(u, v)\) on line \(g\). Find the coordinates of \(P\) that maximize the rectangle’s area, and find the maximum area.
Figure for problem 534877

Hints

- Write the rectangle’s area as the product of its width and height. - Use the line equation to express the height in terms of the width. - Maximize the resulting downward-opening quadratic by finding its vertex.

Solution

1. The rectangle has area \(A = uv\). 2. Since \(P\) lies on \(g\), \(v = -0.75u + 6\). 3. Substitute to obtain \(A(u) = u(-0.75u + 6) = -0.75u^2 + 6u\). 4. This parabola opens downward. Its vertex occurs at \(u = -\frac{6}{2(-0.75)} = 4\). 5. Then \(v = -0.75(4) + 6 = 3\). 6. The maximum area is \(A(4) = 4 \cdot 3 = 12\,\text{ft}^2\).

Answer

\(P = (4, 3)\); maximum area \(12\,\text{ft}^2\)
5350389
The graph shows \(f(x)=x^2+bx+c\) and \(g(x)=2x+c\). The graphs intersect on the y-axis and again at a point on the x-axis. Determine the value of \(b\).
Figure for problem 535038

Hints

- First read the common y-intercept from the graph. - Identify the coordinates of the second intersection. - Substitute a known point into the function equation to determine the missing coefficient.

Solution

1. The shared y-intercept shown in the graph is \(6\), so \(c=6\). 2. The second intersection is the x-intercept \((-3,0)\). Because this point lies on \(f\), \(f(-3)=0\). 3. Substitute \(x=-3\) and \(c=6\): \(0=(-3)^2-3b+6\). 4. Simplify: \(0=15-3b\), so \(3b=15\) and \(b=5\).

Answer

\(b=5\)
5350399
The graph shows a parabola with equation \(p(x)=ax^2-4x+3\) and a line with equation \(g(x)=-x+k\). Determine the value of \(a\).
Figure for problem 535039

Hints

- Use the intersection on the y-axis to determine \(k\). - Read the coordinates of the second intersection from the graph. - Substitute that point into the parabola equation to determine \(a\).

Solution

1. The graphs intersect on the y-axis at \((0,3)\). Since \(g(0)=k\), it follows that \(k=3\), so \(g(x)=-x+3\). 2. The graph shows a second intersection at \((1,2)\). 3. Because this point lies on the parabola, substitute \(x=1\) and \(y=2\): \(2=a-4+3\). 4. Simplify: \(2=a-1\), so \(a=3\).

Answer

\(a=3\)
5144939
A parabola has zeros at \(x = -3\) and \(x = 1\), and its vertex has \(y\)-coordinate \(4\). Find the quadratic function in standard form \(f(x) = ax^2 + bx + c\).

Hints

- Where is the axis of symmetry relative to the two zeros? - How can the vertex help determine the unknown leading coefficient in intercept form? - After finding the leading coefficient, expand the factors carefully.

Solution

1. The axis of symmetry is halfway between the zeros: \(x = \frac{-3 + 1}{2} = -1\). Therefore, the vertex is \((-1, 4)\). 2. Write the function in intercept form: \(f(x) = a(x + 3)(x - 1)\). 3. Substitute the vertex: \(4 = a \cdot 2 \cdot (-2) = -4a\), so \(a = -1\). 4. Expand: \(f(x) = -(x + 3)(x - 1) = -x^2 - 2x + 3\).

Answer

\(f(x) = -x^2 - 2x + 3\)
5145059
An upward-opening parabola of the form \(f(x)=(x-h)^2+k\) passes through the points \(P(-2, 6)\) and \(Q(4, 6)\). a) Use symmetry to determine the vertex of the parabola. b) Write the equation in standard form. c) Determine the range of \(f\) when the domain is restricted to \(x\in[-3, 3]\).

Hints

- For two points with the same y-coordinate, where is the axis of symmetry relative to their x-coordinates? - After finding the axis of symmetry, substitute one point into vertex form. - Check whether the vertex lies in the restricted domain. - Compare the function values at the vertex and at both endpoints.

Solution

1. The points \(P\) and \(Q\) have the same y-coordinate, so their x-coordinates are equally far from the axis of symmetry. The axis is halfway between them: \(h=\frac{-2+4}{2}=1\). 2. Use \(f(x)=(x-1)^2+k\) and substitute \(Q(4, 6)\): \(6=(4-1)^2+k=9+k\), so \(k=-3\). The vertex is \((1, -3)\). 3. Expand the vertex form: \(f(x)=(x-1)^2-3=x^2-2x-2\). 4. The vertex x-coordinate \(1\) lies in \([-3, 3]\), so the minimum value is \(-3\). 5. Evaluate the endpoints: \(f(-3)=(-3-1)^2-3=13\) and \(f(3)=(3-1)^2-3=1\). 6. The maximum value is \(13\), so the range on the restricted domain is \([-3, 13]\).

Answer

a) The vertex is \((1, -3)\). b) \(f(x)=x^2-2x-2\) c) \([-3, 13]\)
5145209
Six points are given: \(A(-3, 4)\), \(B(0, 1)\), \(C(-2, 1)\), \(D(1, 1)\), \(E(4, 4)\), and \(F(2, 0)\). The points can be divided between exactly two graphs of the form \(f(x)=(x-h)^2\). Determine the two possible values of \(h\) and assign each point to the corresponding function.

Hints

- A point on a graph must make the function equation true. - Taking square roots creates two possible cases. - Look for a value of \(h\) that works for several points.

Solution

1. A point \((x, y)\) on the graph satisfies \(y=(x-h)^2\), so \(x-h=\sqrt{y}\) or \(x-h=-\sqrt{y}\). 2. For \(A(-3, 4)\), \(-3-h=2\) or \(-3-h=-2\), giving \(h=-5\) or \(h=-1\). 3. For \(B(0, 1)\), \(-h=1\) or \(-h=-1\), giving \(h=-1\) or \(h=1\). The common value for \(A\) and \(B\) is \(h=-1\). 4. Check \(C(-2, 1)\): \(1=(-2-(-1))^2=1\). Thus, \(A\), \(B\), and \(C\) lie on \(f(x)=(x+1)^2\). 5. Point \(F(2, 0)\) gives \(0=(2-h)^2\), so \(h=2\). 6. Check the remaining points: \((1-2)^2=1\) for \(D\), and \((4-2)^2=4\) for \(E\). Thus, \(D\), \(E\), and \(F\) lie on \(f(x)=(x-2)^2\).

Answer

The two values are \(h=-1\) and \(h=2\). For \(h=-1\), the function is \(f(x)=(x+1)^2\), and the points are \(A\), \(B\), and \(C\). For \(h=2\), the function is \(f(x)=(x-2)^2\), and the points are \(D\), \(E\), and \(F\).
5145319
A translation of the parent parabola \(y=x^2\) has its vertex on the x-axis. a) The point \(A(1, 4)\) lies on the parabola. Find all possible equations that satisfy this condition. b) Explain mathematically why no such parabola can pass through \(B(1, -4)\).

Hints

- If the vertex lies on the x-axis, what is the vertex's y-coordinate? - Compare the situation with vertex form \(f(x)=(x-h)^2+k\). - How many real solutions can an equation of the form \(u^2=a\) have when \(a>0\)? - Can the square of a real number be negative?

Solution

1. A translation of \(y=x^2\) with its vertex on the x-axis has the form \(f(x)=(x-h)^2\). 2. For part a, substitute \(A(1, 4)\): \(4=(1-h)^2\). 3. Taking both square roots gives \(1-h=2\) or \(1-h=-2\). Thus, \(h=-1\) or \(h=3\). 4. The possible equations are \(f_1(x)=(x+1)^2\) and \(f_2(x)=(x-3)^2\). 5. For part b, substituting \(B(1, -4)\) gives \(-4=(1-h)^2\). 6. The square of a real number cannot be negative, so there is no real value of \(h\) and no parabola of the required form through \(B\).

Answer

a) \(f_1(x)=(x+1)^2\) and \(f_2(x)=(x-3)^2\) b) Every function of the form \(f(x)=(x-h)^2\) has \(f(x)\ge 0\) for all real \(x\), so it cannot contain a point with y-coordinate \(-4\).
5145329
The vertex of a translation of the parent parabola \(y=x^2\) lies on the line \(y=2\). The parabola passes through \(P(4, 6)\). 1. Find the equations of all translated parabolas that satisfy these conditions. 2. Determine algebraically whether either parabola intersects the x-axis. Explain your conclusion.

Hints

- What does the line \(y=2\) tell you about the vertex's y-coordinate? - Substitute the given point into vertex form. - What function value is used to find an x-intercept? - Consider the minimum value of each upward-opening parabola.

Solution

1. Since the vertex lies on \(y=2\), the vertex form is \(f(x)=(x-h)^2+2\). 2. Substitute \(P(4, 6)\): \(6=(4-h)^2+2\), so \(4=(4-h)^2\). 3. Taking both square roots gives \(4-h=2\) or \(4-h=-2\). Thus, \(h=2\) or \(h=6\). 4. The two equations are \(f_1(x)=(x-2)^2+2\) and \(f_2(x)=(x-6)^2+2\). 5. For an x-intercept, set \(f(x)=0\): \((x-h)^2+2=0\), so \((x-h)^2=-2\). 6. A square cannot be negative for real \(x\), so neither parabola intersects the x-axis. Equivalently, both parabolas open upward and have minimum value \(2\).

Answer

1. \(f_1(x)=(x-2)^2+2\) and \(f_2(x)=(x-6)^2+2\) 2. Neither parabola intersects the x-axis. Setting either function equal to \(0\) gives a squared expression equal to \(-2\), which has no real solution.
5145469
An upward-opening translation of the parent parabola \(y=x^2\) has its vertex on the x-axis. Its y-intercept is \(P(0, 6.25)\). Find the two possible equations in standard form \(f(x)=x^2+px+q\). Briefly explain why there are two solutions.

Hints

- What is the vertex's y-coordinate when the vertex lies on the x-axis? - Write the general vertex form for this situation. - Substitute the y-intercept into the equation. - Remember that taking square roots produces two cases for a positive value.

Solution

1. Since the vertex lies on the x-axis, the vertex form is \(f(x)=(x-h)^2\). 2. The y-intercept gives \(f(0)=6.25\), so \((0-h)^2=6.25\) and \(h^2=6.25\). 3. Taking both square roots gives \(h=2.5\) or \(h=-2.5\). 4. For \(h=2.5\), \(f_1(x)=(x-2.5)^2=x^2-5x+6.25\). 5. For \(h=-2.5\), \(f_2(x)=(x+2.5)^2=x^2+5x+6.25\). 6. There are two solutions because \(2.5^2=(-2.5)^2=6.25\), so the vertex may lie the same distance to either side of the y-axis.

Answer

The two equations are \(f_1(x)=x^2-5x+6.25\) and \(f_2(x)=x^2+5x+6.25\). There are two solutions because the vertex can be at \(x=2.5\) or \(x=-2.5\), and both positions give the same y-intercept.
5145579
The graph of \(g\) is a translation of the parent parabola \(y=x^2\) and passes through \(A(-2, 3)\) and \(B(4, 3)\). a) Find the equation of \(g\) in vertex form. b) Use symmetry to explain why exactly one such function \(g\) exists.

Hints

- Where is the axis of symmetry when two points have the same y-coordinate? - Write the general vertex form of a translation of \(y=x^2\). - Once the axis is known, how many unknown parameters remain?

Solution

1. Write \(g(x)=(x-h)^2+k\). 2. The points \(A\) and \(B\) have the same y-coordinate, so they are symmetric across the axis of the parabola. The axis lies halfway between their x-coordinates: \(h=\frac{-2+4}{2}=1\). 3. Substitute \(B(4, 3)\): \(3=(4-1)^2+k=9+k\), so \(k=-6\). 4. Therefore, \(g(x)=(x-1)^2-6\). 5. The equal y-coordinates determine the axis \(x=1\) uniquely. Since the leading coefficient is fixed at \(1\), substituting either point then determines \(k\) uniquely. Thus, there is exactly one such function.

Answer

a) \(g(x)=(x-1)^2-6\) b) The equal y-coordinates force the axis of symmetry to be \(x=1\). With leading coefficient \(1\), either point then determines the vertical shift uniquely, so only one function satisfies the conditions.
5145589
Let \(f(x)=x^2\). A translated parent parabola \(g\) satisfies \(g(1)=f(3)\) and \(g(3)=f(1)\). Find the equation of \(g\). Then determine whether \(P(2, 0)\) lies on the graph of \(g\).

Hints

- Evaluate the function values in the two conditions first. - Use the general vertex form of a translated parent parabola. - How can subtracting the two equations eliminate the vertical-shift parameter? - To test a point, compare its y-coordinate with the function value at its x-coordinate.

Solution

1. Evaluate the given function values: \(f(3)=3^2=9\) and \(f(1)=1^2=1\). 2. Write \(g(x)=(x-h)^2+k\). The conditions give \((1-h)^2+k=9\) and \((3-h)^2+k=1\). 3. Subtract the second equation from the first: \((1-h)^2-(3-h)^2=8\). 4. Expand and simplify: \((1-2h+h^2)-(9-6h+h^2)=8\), so \(4h-8=8\) and \(h=4\). 5. Substitute \(h=4\) into \((3-h)^2+k=1\): \((3-4)^2+k=1\), so \(k=0\). 6. Therefore, \(g(x)=(x-4)^2\). 7. Check \(P\): \(g(2)=(2-4)^2=4\). Since \(4\ne 0\), \(P(2, 0)\) is not on the graph.

Answer

The equation is \(g(x)=(x-4)^2\). The point \(P(2, 0)\) is not on the graph because \(g(2)=4\ne 0\).
5145599
The vertex \((h, k)\) of a translated parent parabola \(g\) lies on the line \(y=x-2\). The graph of \(g\) also passes through \(P(4, 2)\). Find all possible equations for \(g\).

Hints

- What relationship does the line equation give between the vertex coordinates? - Substitute that relationship into vertex form. - What type of equation results after substituting the given point? - Check whether the parameter equation has more than one solution.

Solution

1. Since the vertex lies on \(y=x-2\), its coordinates satisfy \(k=h-2\). 2. Write \(g(x)=(x-h)^2+k\), and substitute \(k=h-2\): \(g(x)=(x-h)^2+h-2\). 3. Use \(P(4, 2)\): \(2=(4-h)^2+h-2\). 4. Expand and rearrange: \(2=h^2-7h+14\), so \(h^2-7h+12=0\). 5. Factor: \((h-3)(h-4)=0\). Thus, \(h=3\) or \(h=4\). 6. If \(h=3\), then \(k=1\), giving \(g_1(x)=(x-3)^2+1\). 7. If \(h=4\), then \(k=2\), giving \(g_2(x)=(x-4)^2+2\).

Answer

The two possible functions are \(g_1(x)=(x-3)^2+1\) \(g_2(x)=(x-4)^2+2\).
5145689
Consider the family of functions \(p_c(x) = x^2 - 4x + c\), where \(c\) is a real number. a) Find the value of \(c\) for which the vertex lies on the \(x\)-axis. b) Let \(c = 1\). Find the vertex and the zeros of the function. c) Describe the translation that moves the vertex of \(p_1(x) = x^2 - 4x + 1\) to the origin. Write the equation of the translated function.

Hints

- Rewrite the family in vertex form to see how \(c\) affects the vertex. - What must the vertex's \(y\)-coordinate be when it lies on the \(x\)-axis? - What horizontal and vertical changes move the vertex from part b) to the origin?

Solution

1. Complete the square: \(p_c(x) = x^2 - 4x + c = (x - 2)^2 + c - 4\). The vertex is \((2, c - 4)\). For the vertex to lie on the \(x\)-axis, \(c - 4 = 0\), so \(c = 4\). 2. For \(c = 1\), \(p_1(x) = (x - 2)^2 - 3\), so the vertex is \((2, -3)\). 3. Solve \(x^2 - 4x + 1 = 0\): \(x = \frac{4 \pm \sqrt{16 - 4}}{2} = 2 \pm \sqrt{3}\). 4. Moving \((2, -3)\) to \((0, 0)\) requires a translation \(2\) units left and \(3\) units up. The translated function is \(q(x) = x^2\).

Answer

a) \(c = 4\) b) Vertex \((2, -3)\); zeros \(x = 2 - \sqrt{3}\) and \(x = 2 + \sqrt{3}\) c) Translate \(2\) units left and \(3\) units up; \(q(x) = x^2\).
5254669
Consider \(f(x) = x^2 - 4x + 7\) and \(g(x) = -x^2 + 4x - 5\). a) Find the vertex of each parabola. b) Without solving an equation, explain why the graphs cannot intersect. Use the vertices and opening directions. c) Verify part b) by examining the discriminant of the equation \(f(x) - g(x) = 0\).

Hints

- Write each function in vertex form. - Use each vertex and opening direction to identify the function’s possible y-values. - For the algebraic check, set the functions equal and calculate the discriminant.

Solution

1. Complete the square: \(f(x) = (x - 2)^2 + 3\), so its vertex is \((2, 3)\). 2. Also, \(g(x) = -(x - 2)^2 - 1\), so its vertex is \((2, -1)\). 3. The graph of \(f\) opens upward and has minimum value \(3\), so \(f(x) \ge 3\). The graph of \(g\) opens downward and has maximum value \(-1\), so \(g(x) \le -1\). Therefore, the graphs cannot intersect. 4. Setting \(f(x) = g(x)\) gives \(2x^2 - 8x + 12 = 0\). 5. Its discriminant is \(D = (-8)^2 - 4 \cdot 2 \cdot 12 = 64 - 96 = -32\), confirming that there is no real intersection.

Answer

a) \(f\) has vertex \((2, 3)\), and \(g\) has vertex \((2, -1)\). b) Since \(f(x) \ge 3\) and \(g(x) \le -1\), the graphs cannot intersect. c) \(D = -32\), confirming no real intersection.
5266659
A family of quadratic functions \(f_a\) has zeros \(x=1\) and \(x=a\), where \(a>1\). The vertex of each parabola has y-coordinate \((a-1)^2\). 1) Write \(f_a(x)\) in intercept form, and show that the leading coefficient is \(-4\). 2) Write the function in vertex form and then expand it into standard form. 3) Find the average rate of change of \(f_a\) from \(x=1\) to \(x=2\) in terms of \(a\).

Hints

- Use the two zeros to write intercept form with an unknown leading coefficient. - The vertex x-coordinate is the midpoint of the zeros. - Use the vertex y-coordinate to determine the leading coefficient. - Average rate of change is the change in output divided by the change in input.

Solution

1. Begin with intercept form: \(f_a(x)=c(x-1)(x-a)\). The vertex lies halfway between the zeros, so its x-coordinate is \(\frac{a+1}{2}\). Substituting this value gives the vertex y-coordinate \(-\frac{c}{4}(a-1)^2\). Set this equal to \((a-1)^2\). Since \(a>1\), divide by \((a-1)^2\) to obtain \(c=-4\). Therefore, \(f_a(x)=-4(x-1)(x-a)\). 2. The vertex is \(\left(\frac{a+1}{2}, (a-1)^2\right)\), so vertex form is \(f_a(x)=-4\left(x-\frac{a+1}{2}\right)^2+(a-1)^2\). Expanding gives \(f_a(x)=-4x^2+(4a+4)x-4a\). 3. Since \(f_a(1)=0\) and \(f_a(2)=-4(2-1)(2-a)=4a-8\), the average rate of change is \(\frac{f_a(2)-f_a(1)}{2-1}=4a-8\).

Answer

1) \(f_a(x)=-4(x-1)(x-a)\) 2) Vertex form: \(f_a(x)=-4\left(x-\frac{a+1}{2}\right)^2+(a-1)^2\) Standard form: \(f_a(x)=-4x^2+(4a+4)x-4a\) 3) The average rate of change is \(4a-8\).
5325839
Consider the family \(f_a(x)=x^2-2ax+a\), where \(a\in\mathbb{R}\). Four graphs from the family are labeled p, q, r, and s in the figure. a) Estimate the common intersection point \(P\) from the figure, and then verify it algebraically. b) Find the vertex in terms of \(a\). c) Find the equation of the locus containing all vertices. d) Identify the displayed graphs that are tangent to the x-axis, and calculate their parameter values.
Figure for problem 532583

Hints

- Set two family members with different parameter values equal. - Complete the square to find the vertex. - Replace the parameter with the vertex x-coordinate. - Tangency to the x-axis occurs when the vertex y-coordinate is zero.

Solution

1. Set two family members equal: \(x^2-2ax+a=x^2-2bx+b\). For \(a\neq b\), this simplifies to \((a-b)(1-2x)=0\), so \(x=\frac{1}{2}\). Substitution gives \(y=\frac{1}{4}\). Thus \(P\left(\frac{1}{2}, \frac{1}{4}\right)\). 2. Complete the square: \(f_a(x)=(x-a)^2-a^2+a\). Therefore, the vertex is \((a, -a^2+a)\). 3. Since the vertex x-coordinate is \(x=a\), the locus is \(y=-x^2+x\). 4. A parabola is tangent to the x-axis when its vertex has y-coordinate zero. Solve \(-a^2+a=0\), giving \(a=0\) or \(a=1\). In the figure these are graphs q and r, respectively.

Answer

a) \(P\left(\frac{1}{2}, \frac{1}{4}\right)\) b) \((a, -a^2+a)\) c) \(y=-x^2+x\) d) Graph q has \(a=0\), and graph r has \(a=1\).
5334389
A small robot makes a jump whose path is modeled by \(h(x)=-0.5x^2+2x+2.5\), where \(x\) is the horizontal distance and \(h\) is the height, both in inches. a) Use completing the square to rewrite the function in vertex form. b) Use the vertex form to find the zeros. At what horizontal distance does the robot land, where \(h=0\)? c) Write the function in intercept form. d) Check your results using the graph.
Figure for problem 533438

Hints

- Factor the leading coefficient from the first two terms. - Complete the square inside the parentheses. - Set the vertex form equal to zero and use the square-root property. - Intercept form has the structure \(a(x-r_1)(x-r_2)\).

Solution

1. Factor \(-0.5\) from the quadratic and linear terms: \(h(x)=-0.5(x^2-4x)+2.5\). 2. Complete the square: \(h(x)=-0.5\left((x-2)^2-4\right)+2.5=-0.5(x-2)^2+4.5\). 3. Set the vertex form equal to zero: \(-0.5(x-2)^2+4.5=0\). 4. Solve: \((x-2)^2=9\), so \(x-2=\pm3\). The zeros are \(x=-1\) and \(x=5\). 5. In context, the robot lands at \(x=5\,\text{in}\); the negative zero is outside the forward jump. 6. Using the zeros and leading coefficient, the intercept form is \(h(x)=-0.5(x+1)(x-5)\). 7. The graph shows the vertex \((2, 4.5)\) and x-intercepts \((-1, 0)\) and \((5, 0)\), confirming the results.

Answer

a) \(h(x)=-0.5(x-2)^2+4.5\) b) The zeros are \(x=-1\) and \(x=5\); the robot lands at \(5\,\text{in}\). c) \(h(x)=-0.5(x+1)(x-5)\) d) The graph confirms the vertex \((2, 4.5)\) and x-intercepts \((-1, 0)\) and \((5, 0)\).
5343659
Consider the family of functions \(g_k(x)=kx^2+(2k+1)x+2\), where \(k\ne0\). a) Show that every graph passes through the common points \(A(-2, 0)\) and \(B(0, 2)\). b) The figure shows graphs p–s for \(k\in\{-1, -0.5, 0.5, 1\}\). Match each parameter value to a graph. c) Find \(k\) so that \(x=1\) is a zero.
Figure for problem 534365

Hints

- Substitute the coordinates of each common point. - Use opening direction, symmetry, vertices, and zeros to match the parabolas. - Substitute \(x=1\) and set the result equal to zero.

Solution

1. Substitution gives \(g_k(0)=2\) and \(g_k(-2)=4k-2(2k+1)+2=0\), independent of \(k\). 2. Graph p is \(g_{-1}(x)=-x^2-x+2\), which opens downward and has zeros \(-2\) and \(1\). 3. Graph q is \(g_{-0.5}(x)=-0.5x^2+2\), the downward-opening graph symmetric about the y-axis. 4. Graph r is \(g_{0.5}(x)=0.5(x+2)^2\), which is tangent to the x-axis at \((-2, 0)\). 5. Graph s is \(g_1(x)=x^2+3x+2\), with zeros \(-2\) and \(-1\). 6. For a zero at \(x=1\), \(g_k(1)=3k+3=0\), so \(k=-1\).

Answer

a) \(g_k(-2)=0\) and \(g_k(0)=2\) b) p: \(k=-1\); q: \(k=-0.5\); r: \(k=0.5\); s: \(k=1\) c) \(k=-1\)

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