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Transformations of exponential functions

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52607512
Let \(f(x)=e^x\). The graph of \(g\) is obtained from the graph of \(f\) by applying these transformations in the order shown: 1. Reflect across the x-axis. 2. Stretch vertically by a factor of \(2.5\). 3. Shift \(3\) units left. 4. Shift \(1\) unit down. Write an equation for \(g(x)\).

Hints

- How does a horizontal shift change the input of a function, while a vertical shift changes its output? - How is a reflection across the x-axis represented in a function equation? - Apply the transformations in the stated order.

Solution

1. Reflecting across the x-axis gives \(-e^x\). 2. A vertical stretch by a factor of \(2.5\) gives \(-2.5e^x\). 3. Shifting \(3\) units left replaces \(x\) with \(x+3\), giving \(-2.5e^{x+3}\). 4. Shifting \(1\) unit down gives \(g(x)=-2.5e^{x+3}-1\).

Answer

\(g(x)=-2.5e^{x+3}-1\)
52609412
Consider the family of functions \(g_t(x)=e^x+2t\), where \(t\in\mathbb{R}\). 1. Find \(g_t'(x)\). 2. Describe how the graph of \(g_t\) is obtained from the graph of \(f(x)=e^x\), including the role of \(t\). 3. Find \(t\) so that the graph crosses the x-axis at \(x=0\).

Hints

- A term containing no \(x\) has derivative \(0\). - An added constant produces a vertical translation. - An x-intercept has y-coordinate \(0\). - Recall that \(e^0=1\).

Solution

1. Because \(2t\) is constant with respect to \(x\), \(g_t'(x)=e^x\). 2. The graph is shifted vertically by \(2t\) units. It shifts up when \(t>0\) and down when \(t<0\). 3. Crossing the x-axis at \(x=0\) requires \(g_t(0)=0\). Thus, \(1+2t=0\), so \(t=-\frac{1}{2}\).

Answer

1. \(g_t'(x)=e^x\) 2. A vertical shift of \(2t\) units. 3. \(t=-\frac{1}{2}\)
52836312
Let \(f(x)=3^x\). a) By what factor does \(f(x)\) change when the input increases by \(5\)? b) By how much must the input decrease so that the function value becomes \(\frac{1}{9}\) of its original value?

Hints

- Express \(f(x+5)\) in terms of \(f(x)\) using exponent properties. - Compare the new function value with the original by forming a ratio. - Rewrite \(\frac{1}{9}\) as a power of \(3\). - Set up an equation with the same base on both sides.

Solution

1. a) Compare the new and original values: \(\frac{f(x+5)}{f(x)}=\frac{3^{x+5}}{3^x}=3^5=243\). The function value is multiplied by \(243\). 2. b) Let the input decrease by \(k\). Then \(\frac{f(x-k)}{f(x)}=\frac{3^{x-k}}{3^x}=3^{-k}\). 3. Set \(3^{-k}=\frac{1}{9}=3^{-2}\). Therefore, \(k=2\), so the input must decrease by \(2\).

Answer

a) A factor of \(243\) b) Decrease the input by \(2\).
52985112
Let \(f(x)=e^x\). The graph of \(g\) is obtained by shifting the graph of \(f\) \(2\) units right and \(5\) units down. a) Write an equation for \(g\). b) Give the equation of the horizontal asymptote of \(g\). c) Find the exact coordinates of the y-intercept of \(g\).

Hints

- How do changes inside the input differ from constants added to the entire function? - Start with the horizontal asymptote of \(e^x\) and apply the vertical shift. - What is the x-coordinate of every point on the y-axis?

Solution

1. Shifting \(2\) units right replaces \(x\) with \(x-2\), and shifting \(5\) units down subtracts \(5\). Thus, \(g(x)=e^{x-2}-5\). 2. The horizontal asymptote of \(e^x\) is \(y=0\). Shifting the graph down \(5\) units changes the asymptote to \(y=-5\). 3. At the y-intercept, \(x=0\). Therefore, \(g(0)=e^{-2}-5\), so the y-intercept is \((0, e^{-2}-5)\).

Answer

a) \(g(x)=e^{x-2}-5\) b) \(y=-5\) c) \((0, e^{-2}-5)\)
52985512
The graph of \(f(x)=e^x\) is stretched vertically by a factor of \(2\) and then shifted \(3\) units to the right. a) Write an equation for the resulting function \(g\). b) Find the exact coordinates of the y-intercept of \(g\).

Hints

- How does a vertical stretch affect the entire function expression? - What change to the input shifts a graph to the right? - What x-value identifies a y-intercept?

Solution

1. A vertical stretch by a factor of \(2\) gives \(2e^x\). 2. Shifting \(3\) units right replaces \(x\) with \(x-3\), so \(g(x)=2e^{x-3}\). 3. At the y-intercept, \(x=0\). Therefore, \(g(0)=2e^{-3}\), and the y-intercept is \((0, 2e^{-3})\).

Answer

a) \(g(x)=2e^{x-3}\) b) \((0, 2e^{-3})\)
53267112
Four graphs labeled \(A\), \(B\), \(C\), and \(D\) are shown in the coordinate plane. Match each graph with one equation from the list. Two equations will not be used. (1) \(y=e^x\) (2) \(y=e^{-x}\) (3) \(y=e^x-3\) (4) \(y=-e^x+2\) (5) \(y=e^{x-3}\) (6) \(y=-e^{-x}\) Briefly justify each match using features such as intercepts, monotonicity, and end behavior.
Figure for problem 532671

Hints

- Evaluate each equation at \(x=0\) to compare y-intercepts. - Determine which graphs increase and which decrease. - Compare horizontal asymptotes and end behavior. - Identify reflections and vertical shifts.

Solution

1. Graph \(A\) is increasing, stays above the x-axis, has y-intercept \((0, 1)\), and approaches \(y=0\) as \(x\to-\infty\). Thus, \(A\) matches (1), \(y=e^x\). 2. Graph \(B\) is decreasing, stays above the x-axis, has y-intercept \((0, 1)\), and approaches \(y=0\) as \(x\to\infty\). Thus, \(B\) matches (2), \(y=e^{-x}\). 3. Graph \(C\) is the basic exponential graph shifted down \(3\) units. It has y-intercept \((0, -2)\) and horizontal asymptote \(y=-3\). Thus, \(C\) matches (3), \(y=e^x-3\). 4. Graph \(D\) is decreasing, has y-intercept \((0, 1)\), and approaches \(y=2\) as \(x\to-\infty\). Thus, \(D\) matches (4), \(y=-e^x+2\).

Answer

\(A\): (1) \(B\): (2) \(C\): (3) \(D\): (4)
53403512
The function \(f(x)=1+2(0.5)^x\) models exponential decay. Its graph approaches the horizontal asymptote \(y=1\). The figure shows a horizontal band of total width \(0.4\), centered on the asymptote. Determine by calculation whether the graph lies inside or outside the band at \(x=3\) and at \(x=4\).
Figure for problem 534035

Hints

- Use the band width to find the upper and lower boundaries. - Evaluate the function at each specified x-value. - Compare each function value with both band boundaries.

Solution

1. A total width of \(0.4\) means the band extends \(0.2\) above and below \(y=1\). Its boundaries are \(y=0.8\) and \(y=1.2\). 2. \(f(3)=1+2(0.5)^3=1.25\). Since \(1.25>1.2\), the graph is outside the band at \(x=3\). 3. \(f(4)=1+2(0.5)^4=1.125\). Since \(0.8\leq1.125\leq1.2\), the graph is inside the band at \(x=4\).

Answer

At \(x=3\), the graph is outside the band because \(f(3)=1.25\). At \(x=4\), it is inside the band because \(f(4)=1.125\).
52606312
Let \(f(x)=5-e^x\). Determine whether each statement about the graph of \(f\) is true or false. Briefly justify each answer. a) The graph crosses the x-axis at \(x=\ln(5)\). b) The line \(y=5\) is a horizontal asymptote as \(x\to-\infty\). c) The function \(f\) is strictly increasing over its entire domain. d) The graph of \(f\) has an inflection point at the origin. e) The y-intercept is \((0, 4)\).

Hints

- How can you find where a graph intersects an axis? - What happens to \(e^x\) as \(x\) becomes very negative? - How does reflection across the x-axis affect whether a graph increases or decreases? - Does a reflection and vertical shift create a change in concavity for an exponential graph? - Recall the value of \(e^0\).

Solution

1. Set \(f(x)=0\): \(5-e^x=0\), so \(e^x=5\) and \(x=\ln(5)\). Statement a is true. 2. As \(x\to-\infty\), \(e^x\to0\), so \(5-e^x\to5\). Statement b is true. 3. The graph of \(e^x\) is strictly increasing. Reflecting it across the x-axis makes \(-e^x\) strictly decreasing, and shifting it upward does not change monotonicity. Statement c is false. 4. The graph of \(-e^x\) is concave down everywhere, and a vertical shift does not change concavity. Therefore, there is no inflection point. Statement d is false. 5. Since \(f(0)=5-e^0=5-1=4\), the y-intercept is \((0, 4)\). Statement e is true.

Answer

a) True; solving \(5-e^x=0\) gives \(x=\ln(5)\). b) True; \(f(x)\to5\) as \(x\to-\infty\). c) False; \(f\) is strictly decreasing. d) False; the graph is concave down everywhere. e) True; \(f(0)=4\).
52607612
Consider \(g(x)=4-2e^{0.5x-1}\). Describe, step by step, one sequence of transformations that produces the graph of \(g\) from the graph of \(f(x)=e^x\).

Hints

- First factor the coefficient of \(x\) from the entire exponent. - How does a coefficient multiplying \(x\) inside the exponent affect horizontal scaling? - What does the negative coefficient outside the exponential function do to the graph? - Which constant determines the horizontal asymptote?

Solution

1. Rewrite the exponent by factoring: \(0.5x-1=0.5(x-2)\), so \(g(x)=-2e^{0.5(x-2)}+4\). 2. Replacing \(x\) with \(0.5x\) stretches the graph horizontally by a factor of \(2\). 3. Replacing \(x\) with \(x-2\) after that stretch shifts the graph \(2\) units right, producing \(e^{0.5(x-2)}\). 4. Multiplying by \(-2\) stretches the graph vertically by a factor of \(2\) and reflects it across the x-axis. 5. Adding \(4\) shifts the graph \(4\) units up. The result is \(g(x)=-2e^{0.5(x-2)}+4\).

Answer

1. Stretch horizontally by a factor of \(2\). 2. Shift \(2\) units right. 3. Stretch vertically by a factor of \(2\). 4. Reflect across the x-axis. 5. Shift \(4\) units up.
52613012
Let \(k(x)=-e^{3-x}+5\). Describe a sequence of transformations that produces the graph of \(k\) from the graph of \(f(x)=e^x\). Then give the equation of the horizontal asymptote of the graph of \(k\).

Hints

- Rewrite the exponent so the horizontal shift is visible. - What transformation is represented by a negative sign on \(x\) inside the exponent? - How does the constant added outside the exponential expression affect the horizontal asymptote? - What does multiplying the entire exponential expression by \(-1\) do?

Solution

1. Rewrite the exponent as \(3-x=-(x-3)\). 2. Replacing \(x\) with \(-x\) reflects the graph of \(e^x\) across the y-axis, producing \(e^{-x}\). 3. Replacing \(x\) with \(x-3\) shifts that graph \(3\) units right, producing \(e^{-(x-3)}=e^{3-x}\). 4. Multiplying by \(-1\) reflects the graph across the x-axis, producing \(-e^{3-x}\). 5. Adding \(5\) shifts the graph \(5\) units up, producing \(k(x)=-e^{3-x}+5\). 6. As \(x\to\infty\), \(e^{3-x}\to0\), so \(k(x)\to5\). The horizontal asymptote is \(y=5\).

Answer

One possible sequence is: reflect across the y-axis, shift \(3\) units right, reflect across the x-axis, and shift \(5\) units up. The horizontal asymptote is \(y=5\).
52634012
Analyze the function \(g(x)=2^{-x^2+1}\). a) Verify algebraically whether its graph is symmetric about the y-axis. b) Find the coordinates of the highest point on the graph. c) Find the limits of \(g(x)\) as \(x\to\infty\) and as \(x\to-\infty\). Explain the geometric meaning of these limits.

Hints

- Test whether \(g(-x)=g(x)\). - First determine where the exponent \(-x^2+1\) is greatest. - Analyze the exponent as \(|x|\) becomes large.

Solution

1. \(g(-x)=2^{-(-x)^2+1}=2^{-x^2+1}=g(x)\), so \(g\) is even and its graph is symmetric about the y-axis. 2. Because the base \(2\) is greater than \(1\), \(g(x)\) is largest when the exponent \(-x^2+1\) is largest. This occurs at \(x=0\), where \(g(0)=2\). The highest point is \((0, 2)\). 3. As \(x\to\infty\) or \(x\to-\infty\), the exponent \(-x^2+1\to-\infty\). Therefore, \(g(x)\to0\) in both directions. 4. Geometrically, the x-axis, \(y=0\), is a horizontal asymptote on both ends of the graph.

Answer

a) Yes; \(g(-x)=g(x)\), so the graph is symmetric about the y-axis. b) \((0, 2)\) c) \(g(x)\to0\) as \(x\to\infty\) and as \(x\to-\infty\); \(y=0\) is a horizontal asymptote.
52663912
Let \(f(x)=e^x\), and let \(G_f\) denote its graph. a) The graph of \(g\) is obtained by shifting \(G_f\) \(3\) units left. Show algebraically that \(G_g\) can also be obtained by stretching \(G_f\) vertically, and find the vertical scale factor \(k\). b) The graph \(G_h\) is obtained by scaling \(G_f\) vertically by \(k=\frac{1}{e^2}\). Find the horizontal shift that also transforms \(G_f\) into \(G_h\), and state its direction.

Hints

- How does a horizontal shift change the input of the function? - Use the product rule for powers with the same base. - Rewrite the constant scale factor as a power of \(e\). - How does the sign in \(x-c\) determine the direction of a horizontal shift?

Solution

1. A shift \(3\) units left replaces \(x\) with \(x+3\), so \(g(x)=e^{x+3}\). 2. Using exponent rules, \(e^{x+3}=e^3e^x=e^3f(x)\). Therefore, the same graph is produced by a vertical stretch with scale factor \(k=e^3\). 3. For part b, \(h(x)=\frac{1}{e^2}e^x=e^{-2}e^x=e^{x-2}=f(x-2)\). 4. Replacing \(x\) with \(x-2\) shifts the graph \(2\) units right.

Answer

a) \(g(x)=e^3e^x\), so \(k=e^3\). b) Shift \(G_f\) \(2\) units to the right.
52769312
Write one possible exponential function based on \(e^x\) that satisfies each condition. a) The graph has horizontal asymptote \(y=5\) and y-intercept \((0, 6)\). b) The graph has horizontal asymptote \(y=-2\) and y-intercept \((0, 3)\).

Hints

- Use a transformed exponential function of the form \(ae^x+c\). - The vertical shift determines the horizontal asymptote. - Substitute \(x=0\) to use the y-intercept. - Since \(e^0=1\), the intercept gives a simple equation for \(a\).

Solution

1. Use the form \(F(x)=ae^x+c\), whose horizontal asymptote is \(y=c\). 2. For part a, \(c=5\). The y-intercept condition gives \(a+5=6\), so \(a=1\). One solution is \(F(x)=e^x+5\). 3. For part b, \(c=-2\). The y-intercept condition gives \(a-2=3\), so \(a=5\). One solution is \(F(x)=5e^x-2\).

Answer

a) \(F(x)=e^x+5\) b) \(F(x)=5e^x-2\)
52789112
Let \(f(x)=4-2e^x\), with domain \(\mathbb{R}\). 1. Determine the end behavior as \(x\to\infty\) and as \(x\to-\infty\). 2. State whether \(f\) is increasing or decreasing, and give its range. 3. Find the y-intercept of the graph.

Hints

- Recall the end behavior of \(e^x\). - Consider the effect of multiplying by a negative number. - The vertical shift determines the horizontal asymptote. - Set \(x=0\) to find the y-intercept.

Solution

1. As \(x\to\infty\), \(e^x\to\infty\), so \(f(x)\to-\infty\). As \(x\to-\infty\), \(e^x\to0\), so \(f(x)\to4\). Thus, \(y=4\) is a horizontal asymptote. 2. Since \(e^x\) is strictly increasing, \(-2e^x\) is strictly decreasing. Adding \(4\) does not change monotonicity, so \(f\) is strictly decreasing. The function approaches but never reaches \(4\), and it is unbounded below, so its range is \((-\infty, 4)\). 3. \(f(0)=4-2e^0=2\), so the y-intercept is \((0, 2)\).

Answer

1. \(\lim_{x\to\infty}f(x)=-\infty\); \(\lim_{x\to-\infty}f(x)=4\) 2. Strictly decreasing; range \((-\infty, 4)\) 3. \((0, 2)\)
52791012
Let \(g(x)=e^x\) and \(f(x)=4e^{0.5x-2}-1\). Describe one sequence of transformations that produces the graph of \(f\) from the graph of \(g\).

Hints

- Factor the coefficient of \(x\) from the entire exponent. - A coefficient multiplying \(x\) inside the exponent changes horizontal scale. - Factors and constants outside the exponential affect outputs. - Check the sequence by reconstructing the final exponent.

Solution

1. Factor the exponent: \(0.5x-2=0.5(x-4)\). 2. Horizontally stretch the graph of \(g\) by a factor of \(2\), producing \(e^{0.5x}\). 3. Shift right \(4\) units, producing \(e^{0.5(x-4)}\). 4. Vertically stretch by a factor of \(4\). 5. Shift down \(1\) unit.

Answer

Horizontally stretch by a factor of \(2\), shift right \(4\) units, vertically stretch by a factor of \(4\), and shift down \(1\) unit.
52836412
Let \(h(x)=6^x\). a) Use logarithms to find the amount \(k\) by which the input must increase so that the function value is multiplied by \(100\). Round to three decimal places. b) Determine how this value of \(k\) changes for \(g(x)=36^x\). Justify your answer using algebra or exponent properties.

Hints

- Set up an equation using \(h(x+k)=100h(x)\). - Solve an equation of the form \(a^k=b\) with logarithms. - Express \(36\) as a power of \(6\). - Use the power-of-a-power property to compare the two equations.

Solution

1. a) Set \(h(x+k)=100h(x)\): \(6^{x+k}=100\cdot6^x\). 2. Divide by \(6^x\): \(6^k=100\). Therefore, \(k=\log_6(100)=\frac{\log(100)}{\log(6)}\approx2.570\). 3. b) For \(g\), the equation is \(36^k=100\). Since \(36=6^2\), \(6^{2k}=100\). 4. Compared with \(6^{k_{\!6}}=100\), this gives \(2k_{\!36}=k_{\!6}\). Thus, \(k_{\!36}=\frac{1}{2}k_{\!6}\approx1.285\).

Answer

a) \(k\approx2.570\) b) The required increase is halved: \(k\approx1.285\).
52983212
Let \(f(x)=4^x\). 1. Rewrite \(f\) using base \(e\). 2. The graph of \(g\) is the reflection of the graph of \(f\) across the y-axis. Write \(g\) both in the form \(g(x)=\left(\frac{1}{b}\right)^x\) and using base \(e\).

Hints

- How can a positive number be written using \(e\) and the natural logarithm? - What change to the input reflects a graph across the y-axis? - Recall the meaning of a negative exponent.

Solution

1. Since \(4=e^{\ln(4)}\), \(f(x)=\left(e^{\ln(4)}\right)^x=e^{x\ln(4)}\). 2. Reflection across the y-axis replaces \(x\) with \(-x\), so \(g(x)=f(-x)=4^{-x}\). 3. Using exponent rules, \(4^{-x}=\left(4^{-1}\right)^x=\left(\frac{1}{4}\right)^x\). 4. In base \(e\), \(g(x)=e^{-x\ln(4)}\).

Answer

1. \(f(x)=e^{x\ln(4)}\) 2. \(g(x)=\left(\frac{1}{4}\right)^x=e^{-x\ln(4)}\)
52985212
A function has the form \(h(x)=ae^x+c\). Its graph is obtained from the graph of \(e^x\) by vertical scaling and translation. The line \(y=-2\) is the horizontal asymptote of the graph of \(h\). The graph of \(h\) also passes through the point where the line \(y=x+1\) crosses the y-axis. Find \(a\), \(c\), and the equation of \(h\).

Hints

- Which parameter determines the horizontal asymptote? - Find where \(y=x+1\) crosses the y-axis. - Substitute the known point into the general equation. - Recall the value of \(e^0\).

Solution

1. For \(h(x)=ae^x+c\), the horizontal asymptote is \(y=c\). Therefore, \(c=-2\). 2. The line \(y=x+1\) crosses the y-axis at \((0, 1)\), so \(h(0)=1\). 3. Substitute into \(h(x)=ae^x-2\): \(1=ae^0-2=a-2\). 4. Thus, \(a=3\), and \(h(x)=3e^x-2\).

Answer

\(a=3\), \(c=-2\), and \(h(x)=3e^x-2\)
52985412
Let \(f(x)=e^x\) and \(h(x)=3e^x\). The graph of \(h\) can be obtained by shifting the graph of \(f\) horizontally. Find the distance and direction of the shift.

Hints

- Write the scale factor \(3\) as a power with base \(e\). - Combine powers with the same base. - What direction is represented by replacing \(x\) with \(x+c\)?

Solution

1. Write \(3=e^{\ln(3)}\). Then \(h(x)=e^{\ln(3)}e^x=e^{x+\ln(3)}\). 2. Since \(h(x)=f(x+\ln(3))\), the graph of \(f\) is shifted \(\ln(3)\) units to the left.

Answer

Shift the graph \(\ln(3)\) units to the left.
52985612
The graph of \(f(x)=e^x\) is reflected across the x-axis and shifted \(5\) units down. a) Find \(h_1(x)\) when the reflection is performed first and the shift second. b) Reverse the order of the transformations to obtain \(h_2(x)\). Compare \(h_1\) and \(h_2\), and determine whether the order changes the result.

Hints

- How does reflection across the x-axis change each output? - Apply the second transformation to the entire result of the first. - Compare the final expressions for all x-values.

Solution

1. Reflecting \(f\) across the x-axis gives \(-e^x\). Shifting that graph \(5\) units down gives \(h_1(x)=-e^x-5\). 2. Reversing the order, first shift \(f\) down \(5\) units to obtain \(e^x-5\). 3. Reflecting the entire shifted function across the x-axis gives \(h_2(x)=-(e^x-5)=-e^x+5\). 4. Since \(-e^x-5\ne-e^x+5\), the two orders produce different functions.

Answer

a) \(h_1(x)=-e^x-5\) b) \(h_2(x)=-e^x+5\). The order matters because \(h_1\ne h_2\).
53006712
Let \(f(x)=e^x\). The graph is transformed in two different orders. 1) First shift up \(3\) units, then vertically stretch the entire result by a factor of \(2\). 2) First vertically stretch by a factor of \(2\), then shift up \(3\) units. For each resulting function \(g_1\) and \(g_2\), write the function rule, state the horizontal asymptote, and find the y-intercept.

Hints

- Apply each transformation to the current function, not just to the original exponential term. - Use parentheses when a vertical stretch follows a vertical shift. - Recall the end behavior of \(e^x\) as \(x\to-\infty\).

Solution

1. For the first order, shift and then scale: \(g_1(x)=2(e^x+3)=2e^x+6\). 2. Since \(e^x\to0\) as \(x\to-\infty\), the horizontal asymptote of \(g_1\) is \(y=6\). Also, \(g_1(0)=2e^0+6=8\), so the y-intercept is \((0, 8)\). 3. For the second order, scale and then shift: \(g_2(x)=2e^x+3\). 4. The horizontal asymptote of \(g_2\) is \(y=3\). Also, \(g_2(0)=2e^0+3=5\), so the y-intercept is \((0, 5)\).

Answer

1) \(g_1(x)=2e^x+6\); horizontal asymptote: \(y=6\); y-intercept: \((0, 8)\) 2) \(g_2(x)=2e^x+3\); horizontal asymptote: \(y=3\); y-intercept: \((0, 5)\)
53006812
Let \(f(x)=e^x\). Two functions are created using the same transformations in different orders. - For \(g\), reflect the graph of \(f\) across the x-axis, then shift it up \(2\) units. - For \(h\), shift the graph of \(f\) up \(2\) units, then reflect the entire result across the x-axis. Write rules for \(g\) and \(h\), and find all real zeros of each function.

Hints

- A reflection across the x-axis multiplies the entire current output by \(-1\). - Pay attention to whether the vertical shift is inside or outside the reflection. - Use the fact that \(e^x\) is always positive.

Solution

1. Reflect first and then shift: \(g(x)=-e^x+2\). 2. Solve \(-e^x+2=0\): \(e^x=2\), so \(x=\ln(2)\). 3. Shift first and then reflect: \(h(x)=-(e^x+2)=-e^x-2\). 4. Since \(e^x>0\) for every real \(x\), \(-e^x-2<0\). Therefore, \(h\) has no real zeros.

Answer

\(g(x)=-e^x+2\) has the zero \(x=\ln(2)\). \(h(x)=-e^x-2\) has no real zeros.
53262912
Consider the family of functions \(f_a(x)=ae^x-2\), where \(a>0\). The figure shows four graphs labeled p, q, r, and s. a) Find the value of \(a\) for each graph. b) Describe how increasing \(a\) changes the y-intercept and the steepness of the graph. c) Find \(f_a'(x)\).
Figure for problem 532629

Hints

- Evaluate the function at \(x=0\). - Read each y-intercept from the graph. - Differentiate while treating \(a\) as a constant.

Solution

1. The y-intercept is \(f_a(0)=a-2\), so \(a\) equals the y-intercept plus \(2\). 2. Graph p has y-intercept \(1\), so \(a=3\). Graph q has y-intercept \(0\), so \(a=2\). Graph r has y-intercept \(-1\), so \(a=1\). Graph s has y-intercept \(-1.5\), so \(a=0.5\). 3. Increasing \(a\) moves the y-intercept upward. Since \(f_a'(x)=ae^x\), increasing \(a\) also increases the slope at every fixed \(x\), making the graph steeper.

Answer

a) p: \(a=3\); q: \(a=2\); r: \(a=1\); s: \(a=0.5\) b) The y-intercept moves upward, and the graph becomes steeper. c) \(f_a'(x)=ae^x\)
53266612
The dashed graph is \(f(x)=e^x\). The graphs of \(g\) and \(h\) are transformations of \(f\). Describe the transformations that produce each graph, and write a function rule for \(g\) and for \(h\).
Figure for problem 532666

Hints

- Compare the horizontal asymptotes of the three graphs. - Track the point \((0, 1)\) on the parent function. - Determine which transformed graph is decreasing. - Use the form \(ae^{x-d}+c\) to organize the transformations.

Solution

1. The graph of \(g\) has horizontal asymptote \(y=-2\), so \(f\) is shifted down \(2\) units. The point \((0, 1)\) on \(f\) corresponds to \((1, -1)\) on \(g\), showing a shift right \(1\) unit. 2. Therefore, \(g(x)=e^{x-1}-2\). 3. The graph of \(h\) is decreasing and has horizontal asymptote \(y=3\). Reflecting \(f\) across the x-axis gives \(-e^x\), and shifting up \(3\) units gives the displayed graph. 4. Therefore, \(h(x)=-e^x+3\).

Answer

\(g\): shift right \(1\) unit and down \(2\) units; \(g(x)=e^{x-1}-2\) \(h\): reflect across the x-axis and shift up \(3\) units; \(h(x)=-e^x+3\)
53403812
The blue graph is \(f(x)=e^x\), and the congruent red graph \(g\) is a translation of \(f\). 1) Describe the translations that produce \(g\). 2) Write the equation of \(g\). 3) Calculate \(g(0)\).
Figure for problem 534038

Hints

- Compare where the two graphs level off to identify the vertical translation. - Track the point \((0, 1)\) from the parent graph. - A shift left places a plus sign with the horizontal shift inside the exponent.

Solution

1. The horizontal asymptote moves from \(y=0\) to \(y=-2\), so the graph shifts down \(2\) units. 2. The point \((0, 1)\) on \(f\) moves to \((-3, -1)\) on \(g\), so the graph shifts left \(3\) units. 3. Thus, \(g(x)=f(x+3)-2=e^{x+3}-2\). 4. Evaluate at \(x=0\): \(g(0)=e^3-2\approx18.09\).

Answer

1) Shift left \(3\) units and down \(2\) units. 2) \(g(x)=e^{x+3}-2\) 3) \(g(0)=e^3-2\approx18.09\)
53444412
The figure shows the graphs of \(u(x)=2^x\) and \(v(x)=x-2\). Define \(f=u\circ v\) and \(g=v\circ u\). a) Use the graphs to find \(f(3)\) and \(g(1)\). b) Use the graphs to solve \(f(x)=1\) and \(g(x)=0\). c) Describe the transformation that maps the graph of \(u\) to the graph of \(f\), and the transformation that maps the graph of \(u\) to the graph of \(g\).
Figure for problem 534444

Hints

- Evaluate the inner function first. - Work backward from the output of the outer function when solving an equation. - Changes inside the exponent produce horizontal shifts; changes outside produce vertical shifts.

Solution

1. Since \(v(3)=1\) and \(u(1)=2\), \(f(3)=2\). Since \(u(1)=2\) and \(v(2)=0\), \(g(1)=0\). 2. The equation \(f(x)=1\) means \(u(v(x))=1\). Since \(u(0)=1\), solve \(v(x)=0\), which gives \(x=2\). The equation \(g(x)=0\) means \(v(u(x))=0\). Since \(v(2)=0\), solve \(u(x)=2\), which gives \(x=1\). 3. Since \(f(x)=2^{x-2}\), its graph is the graph of \(u\) shifted \(2\) units right. Since \(g(x)=2^x-2\), its graph is the graph of \(u\) shifted \(2\) units down.

Answer

a) \(f(3)=2\) and \(g(1)=0\) b) \(f(x)=1\) at \(x=2\); \(g(x)=0\) at \(x=1\) c) \(f\): shift \(2\) units right; \(g\): shift \(2\) units down
53444912
The figure shows four graphs created by composing pairs of these functions: \(f(x)=2^x\), \(g(x)=-x\), and \(h(x)=x-3\). Match graphs p–s to the following compositions: \(k_a(x)=f(g(x))\), \(k_b(x)=g(f(x))\), \(k_c(x)=f(h(x))\), and \(k_d(x)=h(f(x))\).
Figure for problem 534449

Hints

- Write an equation for each composition. - Identify reflections and horizontal or vertical shifts. - Compare y-intercepts and end behavior.

Solution

1. \(f(g(x))=2^{-x}\) is a decreasing exponential function with y-intercept \(1\), so it is graph p. 2. \(g(f(x))=-2^x\) is the graph of \(2^x\) reflected across the x-axis, so it is graph q. 3. \(f(h(x))=2^{x-3}\) is the graph of \(2^x\) shifted \(3\) units right, so it is graph r. 4. \(h(f(x))=2^x-3\) is the graph of \(2^x\) shifted \(3\) units down, so it is graph s.

Answer

p) \(k_a(x)=f(g(x))\) q) \(k_b(x)=g(f(x))\) r) \(k_c(x)=f(h(x))\) s) \(k_d(x)=h(f(x))\)
53458612
Match graphs 1 through 4 to equations from the list. Justify each match using y-intercepts, horizontal asymptotes, or growth rates. More equations are listed than graphs, and equivalent equations may describe the same graph. \(y=e^{x+1}\) \(y=e^x+1\) \(y=2e^x\) \(y=e^x-2\) \(y=e\cdot e^x\) \(y=e^{2x}\) \(y=0.5e^x\)
Figure for problem 534586

Hints

- Substitute \(x=0\) to compare y-intercepts. - Identify each horizontal asymptote. - Compare growth rates at the same positive x-value. - Use exponent rules to identify equivalent equations.

Solution

1. Graph 1 has y-intercept \(2\) and grows like a vertical scaling of \(e^x\). It matches \(y=2e^x\). 2. Graph 2 also has y-intercept \(2\), but its horizontal asymptote is \(y=1\). It matches \(y=e^x+1\). 3. Graph 3 has y-intercept \(e\) and passes through \((-1, 1)\). It matches \(y=e^{x+1}\). Since \(e^{x+1}=e\cdot e^x\), both listed equations describe this graph. 4. Graph 4 has y-intercept \(-1\) and horizontal asymptote \(y=-2\). It matches \(y=e^x-2\).

Answer

Graph 1: \(y=2e^x\) Graph 2: \(y=e^x+1\) Graph 3: \(y=e^{x+1}\) and \(y=e\cdot e^x\) Graph 4: \(y=e^x-2\)
52664012
Consider \(f(x)=e^x\). a) The graph of \(g\) is obtained by stretching the graph of \(f\) horizontally by a factor of \(d=2\). Show that \(g\) is an exponential function of the form \(g(x)=b^x\), and find \(b\). b) Let \(h(x)=5^x\). The graph of \(h\) can be obtained by horizontally scaling the graph of \(f\) by a factor \(d\). Find \(d\), rounded to three decimal places.

Hints

- How does horizontal scaling change the input of a function? - Which exponent rule rewrites \(e^{x/2}\) as a power raised to \(x\)? - Express \(5\) as a power with base \(e\). - Use the inverse relationship between exponential and logarithmic functions.

Solution

1. A horizontal stretch by a factor of \(d\) replaces \(x\) with \(\frac{x}{d}\). For \(d=2\), \(g(x)=f\!\left(\frac{x}{2}\right)=e^{x/2}\). 2. Rewrite \(e^{x/2}=\left(e^{1/2}\right)^x=(\sqrt{e})^x\). Thus, \(b=\sqrt{e}\). 3. To produce \(h(x)=5^x\), require \(e^{x/d}=5^x\). Since \(5^x=e^{x\ln(5)}\), the exponents must satisfy \(\frac{1}{d}=\ln(5)\). 4. Therefore, \(d=\frac{1}{\ln(5)}\approx0.621\). Because \(d<1\), this is a horizontal compression.

Answer

a) \(g(x)=(\sqrt{e})^x\), so \(b=\sqrt{e}\). b) \(d=\frac{1}{\ln(5)}\approx0.621\)
52769412
Construct one function of the form \(h(x)=ae^{g(x)}+c\), where \(g\) is a polynomial and \(a,c\in\mathbb{R}\), whose graph has all three properties: - symmetry about the y-axis, - horizontal asymptote \(y=1\), and - a local minimum at \((0,-1)\). State your choices of \(a\), \(c\), and \(g(x)\), and verify the properties.

Hints

- The vertical shift determines the horizontal asymptote. - Choose an even polynomial exponent for y-axis symmetry. - Make the exponent approach \(-\infty\) at both ends. - Use the given point to determine the remaining coefficient.

Solution

1. Choose \(c=1\) so that \(y=1\) can be the horizontal asymptote. 2. Choose the even polynomial \(g(x)=-x^2\). Then \(g(x)\to-\infty\) as \(x\to\pm\infty\), so \(e^{g(x)}\to0\), and the resulting function is even. 3. Since \(g(0)=0\), the condition \(h(0)=-1\) gives \(a+1=-1\), so \(a=-2\). 4. One valid function is \(h(x)=-2e^{-x^2}+1\). It is even, approaches \(1\) as \(x\to\pm\infty\), and satisfies \(h(0)=-1\). 5. Its derivatives are \(h'(x)=4xe^{-x^2}\) and \(h''(x)=4(1-2x^2)e^{-x^2}\). Since \(h'(0)=0\) and \(h''(0)=4>0\), \((0,-1)\) is a local minimum.

Answer

One valid choice is \(a=-2\), \(c=1\), and \(g(x)=-x^2\), giving \(h(x)=-2e^{-x^2}+1\).

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