CTJan27 Online Year 9 - Exponential Functions

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Defining the Exponential Function y = ab^x

Questions for: Defining the Exponential Function y = ab^x

1

In the exponential function $f(x) = 3(5)^x$, what is the initial value?

$3$

$5$

$x$

$15$

2

In the exponential function $y = 7(0.4)^x$, what is the decay factor?

$7$

$0.4$

$x$

$2.8$

3

Does the function $g(x) = 0.5(1.2)^x$ represent exponential growth or decay?

Exponential growth, because the base $b > 1$.

Exponential decay, because the initial value $a < 1$.

Exponential growth, because the initial value $a > 0$.

Exponential decay, because the base $b > 0$.

4

Which of the following functions represents exponential decay?

$y = 2(3)^x$

$y = 5(0.9)^x$

$y = 0.5(1.1)^x$

$y = (\frac{4}{3})^x$

5

Which of the following functions represents exponential growth?

$f(x) = 10(0.75)^x$

$f(x) = 4(\frac{1}{2})^x$

$f(x) = 8(\frac{5}{4})^x$

$f(x) = 2(1.0)^x$

6

An exponential function has an initial value of 4 and a growth factor of 2. Which equation represents this function?

$y = 2(4)^x$

$y = 4(2)^x$

$y = 4x^2$

$y = 2x^4$

7

A population of a certain species starts at 500 and has a decay factor of $\frac{1}{3}$ per year. Which function models the population $P$ after $t$ years?

$P(t) = 500(\frac{1}{3})^t$

$P(t) = \frac{1}{3}(500)^t$

$P(t) = 500(1 - \frac{1}{3})^t$

$P(t) = 500 - \frac{1}{3}t$

8

In the general exponential function $y = ab^x$, what does the parameter a represent in a real-world context?

The rate of change.

The final amount after a period of time.

The starting amount or initial value.

The time elapsed.

9

For an exponential function $y = ab^x$ (where $a > 0$) to model exponential growth, what must be true about the base b?

$b < 0$

$b = 1$

$0 < b < 1$

$b > 1$

10

Which of the following equations is NOT an exponential function?

$y = 3(0.5)^x$

$y = 7^x$

$y = 5x^3$

$y = (\frac{1}{4})^x$

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Characteristics of Exponential Growth Functions

Questions for: Characteristics of Exponential Growth Functions

11

An exponential function is given by the form $f(x) = b^x$. For this function to represent exponential growth, what must be true about the base, $b$?

$b > 1$

$0 < b < 1$

$b = 1$

$b < 0$

12

What is the y-intercept of the exponential growth function $f(x) = 3(2)^x$?

$(0, 2)$

$(0, 3)$

$(0, 1)$

$(0, 6)$

13

What is the domain of any basic exponential growth function of the form $f(x) = a \cdot b^x$, where $a > 0$ and $b > 1$?

All positive real numbers ($x > 0$)

All real numbers except 0 ($x eq 0$)

All real numbers ($\mathbb{R}$)

All integers

14

Consider the exponential growth function $g(x) = 5(1.5)^x$. What is the range of this function?

All real numbers ($y \in \mathbb{R}$)

All positive real numbers ($y > 0$)

All real numbers greater than 5 ($y > 5$)

All real numbers greater than 1.5 ($y > 1.5$)

15

Which of the following is the horizontal asymptote for the exponential growth function $h(x) = 4^x$?

$y = 1$

$y = 4$

$x = 0$

$y = 0$

16

Which statement accurately describes the behavior of an exponential growth function $f(x) = a \cdot b^x$ where $a > 0$ and $b > 1$?

The function is always decreasing.

The function increases for $x > 0$ and decreases for $x < 0$.

The function is always increasing.

The function has a maximum value at $x=0$.

17

Consider two exponential growth functions: $f(x) = 2^x$ and $g(x) = 3^x$. Which statement is true for $x > 0$?

$f(x)$ always grows faster than $g(x)$.

$g(x)$ always grows faster than $f(x)$.

Both functions grow at the same rate.

$f(x)$ is always greater than $g(x)$.

18

Which of the following scenarios is best modeled by an exponential growth function?

A car depreciating in value by 15% each year.

A population of bacteria that doubles every hour.

The height of a ball dropped from a building.

The cost of a taxi ride which charges 2 dollars per mile plus a flat fee of 3 dollars.

19

How does the graph of $g(x) = 5 \cdot 2^x$ compare to the graph of $f(x) = 2^x$?

The graph of $g(x)$ is shifted 5 units to the right of $f(x)$.

The graph of $g(x)$ is shifted 5 units up from $f(x)$.

The graph of $g(x)$ is a vertical stretch of the graph of $f(x)$ by a factor of 5.

The graph of $g(x)$ is a vertical compression of the graph of $f(x)$ by a factor of 5.

20

An exponential growth function passes through the points $(0, 4)$ and $(1, 12)$. What is the base of this function?

2

3

4

8

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Characteristics of Exponential Decay Functions

Questions for: Characteristics of Exponential Decay Functions

21

Which of the following functions represents exponential decay?

$f(x) = 2(1.5)^x$

$f(x) = 5(0.75)^x$

$f(x) = 0.5(3)^x$

$f(x) = -3(0.5)^x$

22

What is the decay factor of the function $g(t) = 150(0.8)^t$?

$150$

$0.8$

$t$

$1.25$

23

Consider the exponential decay function $f(x) = 2500(0.9)^x$. What is the initial value of the function?

$0.9$

$2500$

$x$

$2250$

24

As the value of $x$ increases towards infinity, what value does the function $f(x) = 10(0.25)^x$ approach?

$10$

$0.25$

$\infty$

$0$

25

What is the domain of any standard exponential decay function of the form $f(x) = a \cdot b^x$, where $a > 0$ and $0 < b < 1$?

$(0, \infty)$

$(a, \infty)$

$(−\infty, \infty)$

$(0, 1)$

26

What is the range of the exponential decay function $f(x) = 75(0.5)^x$?

$(75, \infty)$

$(0, \infty)$

$(−\infty, \infty)$

$(−\infty, 0)$

27

What is the equation of the horizontal asymptote for the function $g(x) = 4(0.6)^x + 5$?

$y = 0$

$y = 4$

$y = 5$

$y = 9$

28

A new car is purchased for 25,000 dollars and depreciates in value by 15% each year. Which function models the value of the car, $V$, after $t$ years?

$V(t) = 25000(1.15)^t$

$V(t) = 25000(0.15)^t$

$V(t) = 25000(0.85)^t$

$V(t) = 25000 - 0.15t$

29

The amount of a certain radioactive substance remaining after $t$ years is given by the function $A(t) = A_0(0.995)^t$. What is the annual decay rate of the substance?

$99.5%$

$0.995%$

$5%$

$0.5%$

30

Consider two exponential decay functions: $f(x) = 100(0.5)^x$ and $g(x) = 100(0.25)^x$. Which statement is true for $x > 0$?

$f(x)$ decays at a faster rate than $g(x)$.

$g(x)$ decays at a faster rate than $f(x)$.

Both functions decay at the same rate.

Both functions represent exponential growth.

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Graphing Exponential Functions and Key Features

Questions for: Graphing Exponential Functions and Key Features

31

What is the y-intercept of the graph of the function $f(x) = 3 \cdot (2)^x$?

$(0, 2)$

$(0, 3)$

$(0, 1)$

$(0, 6)$

32

What is the equation of the horizontal asymptote for the function $g(x) = 5^x - 2$?

$y = 5$

$y = 0$

$y = -2$

$x = -2$

33

Which of the following exponential functions represents exponential decay?

$f(x) = 2 \cdot (1.5)^x$

$g(x) = 0.5 \cdot (3)^x$

$h(x) = 4 \cdot (0.75)^x$

$k(x) = (\frac{5}{3})^x$

34

What is the range of the function $f(x) = -2 \cdot (4)^x + 3$?

$(-\infty, \infty)$

$(3, \infty)$

$(-\infty, 3)$

$(-\infty, -2)$

35

The graph of $f(x) = 2^x$ is transformed to create the graph of $g(x) = 2^{x-3} + 5$. Which of the following describes the transformation?

Shifted 3 units left and 5 units up.

Shifted 3 units right and 5 units up.

Shifted 3 units right and 5 units down.

Shifted 3 units left and 5 units down.

36

Consider the function $f(x) = (\frac{1}{3})^x$. What is the end behavior of the function as $x$ approaches infinity ($x \to \infty$)?

$f(x) \to \infty$

$f(x) \to -\infty$

$f(x) \to 0$

$f(x) \to 1$

37

An exponential function of the form $f(x) = a \cdot b^x$ passes through the points $(0, 5)$ and $(1, 15)$. What is the equation of the function?

$f(x) = 5 \cdot (3)^x$

$f(x) = 3 \cdot (5)^x$

$f(x) = 5 \cdot (\frac{1}{3})^x$

$f(x) = 15 \cdot (\frac{1}{3})^x$

38

What is the domain of any exponential function of the form $f(x) = a \cdot b^{x-h} + k$, where $b > 0$ and $b eq 1$?

${x \in \mathbb{R} | x > h}$

${x \in \mathbb{R} | x > 0}$

All real numbers, $(-\infty, \infty)$

It depends on the value of $k$.

39

Which function has a range of $(-\infty, -4)$?

$f(x) = 3^x - 4$

$f(x) = -3^x + 4$

$f(x) = -3^x - 4$

$f(x) = 3^{-x} - 4$

40

For $x > 0$, which of the following functions grows the fastest?

$f(x) = 2 \cdot (3)^x$

$g(x) = 100 \cdot (2)^x$

$h(x) = 0.5 \cdot (4)^x$

$k(x) = 10 \cdot (3.5)^x$

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Domain, Range, and Horizontal Asymptotes

Questions for: Domain, Range, and Horizontal Asymptotes

41

What is the domain of the exponential function $f(x) = 3^x$?

$x > 0$

$x \ge 0$

All real numbers, $(-\infty, \infty)$

All integers

42

What is the range of the function $g(x) = 5^x$?

All real numbers, $(-\infty, \infty)$

$y > 0$, or $(0, \infty)$

$y \ge 0$, or $[0, \infty)$

$y < 0$, or $(-\infty, 0)$

43

What is the horizontal asymptote of the function $h(x) = (\frac{1}{2})^x$?

$y = 1$

$y = 0$

$x = 0$

$y = \frac{1}{2}$

44

Determine the domain of the function $f(x) = 7^{x-2}$.

$x > 2$

$x eq 2$

All real numbers, $(-\infty, \infty)$

$x < 2$

45

Find the range of the function $f(x) = 2^x + 4$.

$y > 0$

$y > 4$

All real numbers, $(-\infty, \infty)$

$y < 4$

46

What is the equation of the horizontal asymptote for the function $g(x) = 10^x - 3$?

$y = 10$

$y = 0$

$y = -3$

$x = -3$

47

Identify the range of the function $h(x) = -4^x + 1$.

$y > 1$

$y < 1$

$y > -4$

All real numbers, $(-\infty, \infty)$

48

What is the horizontal asymptote of the function $f(x) = -2 \cdot 5^{x+1} - 6$?

$y = -2$

$y = -1$

$y = 5$

$y = -6$

49

Which of the following exponential functions has a horizontal asymptote at $y=2$ and a range of $(2, \infty)$?

$f(x) = 2^x - 2$

$f(x) = -3^x + 2$

$f(x) = 4^x + 2$

$f(x) = 2^{x+2}$

50

An exponential function has a domain of all real numbers and a horizontal asymptote at $y = -5$. Its range is $(-\infty, -5)$. Which of the following could be the function?

$f(x) = 2^x - 5$

$f(x) = -2^x - 5$

$f(x) = -2^x + 5$

$f(x) = 2^{x-5}$

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Vertical and Horizontal Translations of Exponential Graphs

Questions for: Vertical and Horizontal Translations of Exponential Graphs

51

How does the graph of $f(x) = 3^x + 5$ compare to the graph of its parent function $g(x) = 3^x$?

Shifted 5 units to the right.

Shifted 5 units to the left.

Shifted 5 units up.

Shifted 5 units down.

52

The graph of $y = 2^x$ is translated to create the graph of $y = 2^{x-4}$. What is the translation?

4 units up.

4 units down.

4 units to the right.

4 units to the left.

53

Which equation represents the graph of $y = (\frac{1}{2})^x$ translated 3 units to the left and 2 units down?

$y = (\frac{1}{2})^{x-3} - 2$

$y = (\frac{1}{2})^{x+3} - 2$

$y = (\frac{1}{2})^{x-3} + 2$

$y = (\frac{1}{2})^{x+3} + 2$

54

What is the equation of the horizontal asymptote for the function $f(x) = 5^{x+1} - 7$?

$y = -7$

$y = 7$

$y = 1$

$y = -1$

55

Describe the transformation of the parent function $f(x) = 10^x$ to obtain the function $g(x) = 10^{x+6} - 3$.

Shifted 6 units right and 3 units up.

Shifted 6 units right and 3 units down.

Shifted 6 units left and 3 units up.

Shifted 6 units left and 3 units down.

56

The function $f(x) = e^x$ is translated 2 units to the right and 1 unit up. What is the equation of the new function, $g(x)$?

$g(x) = e^{x+2} + 1$

$g(x) = e^{x-2} - 1$

$g(x) = e^{x-2} + 1$

$g(x) = e^{x+2} - 1$

57

What is the y-intercept of the graph of the function $f(x) = 4^{x+1} - 5$?

$(0, -1)$

$(0, -4)$

$(0, 1)$

$(0, -5)$

58

The graph of $y = 2^{x-3} + 4$ has a horizontal asymptote at $y=4$. What is the range of this function?

$(-\infty, 4)$

$(-\infty, 4]$

$(4, \infty)$

$[4, \infty)$

59

Consider the functions $f(x) = 3^{x-2}$ and $g(x) = 3^{x+4}$. How is the graph of $g(x)$ related to the graph of $f(x)$?

$g(x)$ is a translation of $f(x)$ by 6 units to the right.

$g(x)$ is a translation of $f(x)$ by 6 units to the left.

$g(x)$ is a translation of $f(x)$ by 2 units to the left.

$g(x)$ is a translation of $f(x)$ by 2 units to the right.

60

An exponential function of the form $y = 5^x + k$ has a horizontal asymptote at $y = -3$. What is the value of $k$?

$k = 5$

$k = 3$

$k = -5$

$k = -3$

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Stretches, Compressions, and Reflections of Exponential Graphs

Questions for: Stretches, Compressions, and Reflections of Exponential Graphs

61

How is the graph of $y = 5(2^x)$ transformed from the graph of the parent function $y = 2^x$?

A vertical stretch by a factor of 5.

A vertical compression by a factor of $\frac{1}{5}$.

A horizontal stretch by a factor of 5.

A vertical shift up by 5 units.

62

Which equation represents the graph of $y = 3^x$ after a reflection in the x-axis?

$y = 3^{-x}$

$y = (\frac{1}{3})^x$

$y = -3^x$

$y = 3^x - 1$

63

The graph of $f(x) = 4^x$ is transformed to create the graph of $g(x) = 4^{2x}$. Which statement best describes this transformation?

A horizontal stretch by a factor of 2.

A horizontal compression by a factor of $\frac{1}{2}$.

A vertical stretch by a factor of 2.

A vertical compression by a factor of $\frac{1}{2}$.

64

Which transformation maps the graph of $y = 10^x$ onto the graph of $y = 10^{-x}$?

A reflection in the x-axis.

A reflection in the y-axis.

A reflection in the line $y=x$.

A horizontal compression.

65

Describe the transformations applied to the graph of $y = 2^x$ to obtain the graph of $y = -\frac{1}{3} \cdot 2^x$.

A reflection in the y-axis and a vertical stretch by a factor of 3.

A reflection in the x-axis and a vertical compression by a factor of $\frac{1}{3}$.

A reflection in the x-axis and a vertical stretch by a factor of 3.

A reflection in the y-axis and a vertical compression by a factor of $\frac{1}{3}$.

66

The graph of $y = 5^x$ is vertically stretched by a factor of 2 and horizontally compressed by a factor of $\frac{1}{4}$. What is the equation of the transformed function?

$y = 2 \cdot 5^{\frac{1}{4}x}$

$y = \frac{1}{2} \cdot 5^{4x}$

$y = 2 \cdot 5^{4x}$

$y = 4 \cdot 5^{2x}$

67

The point $(2, 9)$ lies on the graph of $f(x) = 3^x$. What are the coordinates of the corresponding point on the graph of $g(x) = -f(2x)$?

$(1, -9)$

$(4, -9)$

$(-1, 9)$

$(2, -18)$

68

Which of the following equations is equivalent to $y = 9 \cdot 3^x$?

$y = 3^{x+2}$

$y = 3^{2x}$

$y = (27)^x$

$y = 3^{x} + 9$

69

The parent function $y=b^x$ (where $b > 1$) has a y-intercept at $(0, 1)$. What is the y-intercept of the transformed function $y = a \cdot b^x$?

$(0, 1)$

$(0, b)$

$(0, a)$

$(a, 1)$

70

Consider the function $f(x) = (\frac{1}{2})^x$. Which of the following transformations would result in the function $g(x) = 2^x$?

A reflection in the x-axis.

A vertical stretch.

A reflection in the y-axis.

A horizontal shift.

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Vertical and Horizontal Translations of Exponential Graphs

Questions for: Vertical and Horizontal Translations of Exponential Graphs

71

The solid red graph is a translation of the dashed blue graph of $y = 2^x$. What is the equation of the red graph?

$y = 2^{x+3}$

$y = 2^x + 3$

$y = 2^x - 3$

$y = 2^{x-3}$

72

The solid red graph shown is a vertical translation of the dashed blue graph, $y = 3^x$. Identify the equation of the red graph.

$y = 3^x + 2$

$y = 3^{x+2}$

$y = 3^{x-2}$

$y = 3^x - 2$

73

How is the graph of $f(x) = (\frac{1}{2})^{x+4}$ obtained by translating the graph of $g(x) = (\frac{1}{2})^x$?

Shifted 4 units to the right

Shifted 4 units up

Shifted 4 units down

Shifted 4 units to the left

74

The graph of the function shown is a translation of the parent function $y=2^x$. What is the equation of the function?

$y = 2^{x+1} + 3$

$y = 2^{x-1} - 3$

$y = 2^{x+3} - 1$

$y = 2^{x-3} + 1$

75

What is the equation of the horizontal asymptote of the graph for the function $f(x) = 5^{x+2} - 6$?

$y = -2$

$y = 2$

$y = -6$

$y = 6$

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Stretches, Compressions, and Reflections of Exponential Graphs

Questions for: Stretches, Compressions, and Reflections of Exponential Graphs

76

The graph of $y = 2^x$ (dashed line) is transformed into the solid line graph shown. Which equation represents the transformed function?

$y = 3 \cdot 2^x$

$y = 2^{x+3}$

$y = 2^x + 3$

$y = \frac{1}{3} \cdot 2^x$

77

The function $y=3^x$ is shown as a dashed line. The solid line represents a transformation of $y=3^x$. Which equation represents the solid line graph?

$y = 3^{-x}$

$y = -3^x$

$y = 3^x - 4$

$y = -(\frac{1}{3})^x$

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