Graph Exponential, Logarithmic, and Trig Functions

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Algebra 2 › Graph Exponential, Logarithmic, and Trig Functions

Questions 1 - 10
1

Describe the end behavior of the exponential function $f(x)=5\cdot(0.6)^x$.

As $x\to \infty$, $f(x)\to 0$; as $x\to -\infty$, $f(x)\to \infty$

As $x\to \infty$, $f(x)\to -\infty$; as $x\to -\infty$, $f(x)\to \infty$

As $x\to \infty$, $f(x)\to 5$; as $x\to -\infty$, $f(x)\to 0$

As $x\to \infty$, $f(x)\to \infty$; as $x\to -\infty$, $f(x)\to 0$

Explanation

This question tests your ability to graph exponential functions by identifying their characteristic features like intercepts, asymptotes, and end behavior. Exponential functions f(x) = $ab^x$ have distinctive features: they have a y-intercept at (0, a) because b⁰ = 1, they never cross the x-axis (no x-intercepts for basic form), and they have a horizontal asymptote at y = 0 (the x-axis) that the graph approaches but never touches. End behavior depends on the base: if b > 1, it's exponential growth (left end approaches 0, right end goes to ∞); if 0 < b < 1, it's exponential decay (left end goes to ∞, right end approaches 0). Transformations like f(x) = $ab^x$ + k shift the horizontal asymptote to y = k! For $f(x)=5·(0.6)^x$, since base 0.6 is between 0 and 1, it's decay, so as x→∞, f(x)→0 and as x→-∞, f(x)→∞. Choice B correctly describes this end behavior for exponential decay. A distractor like Choice A might swap the behaviors, confusing it with growth, but always check if the base is less than 1 for decay. Exponential vs logarithmic graphing comparison: exponentials have y-intercept and horizontal asymptote (HA), while logarithms have x-intercept and vertical asymptote (VA). They're mirror images across y = x! Both never cross their asymptote. For exponentials, check the base: b > 1 means rising (growth), 0 < b < 1 means falling (decay). For logarithms, the graph always rises from left to right (slowly), hugging the VA on the left and flattening as it goes right. These characteristic shapes are instantly recognizable!

2

What is the horizontal asymptote of the exponential function $p(x)=2e^{x}+4$?​

$x=4$

$x=0$

$y=0$

$y=4$

Explanation

This question tests your ability to graph exponential functions by identifying their horizontal asymptote after a transformation. Exponential functions f(x) = $ab^x$ have distinctive features: they have a y-intercept at (0, a) because b⁰ = 1, they never cross the x-axis (no x-intercepts for basic form), and they have a horizontal asymptote at y = 0 (the x-axis) that the graph approaches but never touches. End behavior depends on the base: if b > 1, it's exponential growth (left end approaches 0, right end goes to ∞); if 0 < b < 1, it's exponential decay (left end goes to ∞, right end approaches 0). Transformations like f(x) = $ab^x$ + k shift the horizontal asymptote to y = k! For p(x) = $2e^x$ + 4, this is an exponential growth function (since e ≈ 2.718 > 1) with a vertical shift of +4. The parent function $2e^x$ has horizontal asymptote y = 0, but adding 4 shifts the entire graph up 4 units, so the horizontal asymptote shifts from y = 0 to y = 4. Choice C correctly identifies the horizontal asymptote as y = 4. Choice A gives the parent function's asymptote without the shift, B and D suggest vertical asymptotes (x = something), which exponentials don't have. Remember: for f(x) = $ab^x$ + k, the horizontal asymptote is always y = k, representing the value the function approaches but never reaches as x → -∞ for growth functions!

3

What are the period and amplitude of $t(x)=2\cos\left(\tfrac{1}{2}x\right)$?​

Period $=\pi$; amplitude $=2$

Period $=4\pi$; amplitude $=2$

Period $=\pi$; amplitude $=\tfrac{1}{2}$

Period $=2\pi$; amplitude $=4$

Explanation

This question tests your ability to graph trigonometric functions by identifying period and amplitude from the function's equation. Trigonometric functions like f(x) = a·sin(bx) + d have periodic (repeating) graphs with three key features: amplitude |a| is the vertical distance from the midline to a peak, period 2π/|b| is the horizontal length of one complete cycle, and midline y = d is the horizontal center line the graph oscillates around. The graph oscillates between y = d - |a| (minimum) and y = d + |a| (maximum), repeating this wave pattern every 2π/|b| units. For f(x) = 3sin(2x) + 1: amplitude 3, period π, midline y = 1, oscillating between -2 and 4. For t(x) = 2cos(½x), we identify: amplitude = |2| = 2 (the vertical stretch from midline to peak), and period = 2π/|½| = 2π/(½) = 2π × 2 = 4π (one complete wave every 4π units - the smaller b value stretches the wave horizontally). Choice B correctly identifies period = 4π and amplitude = 2. Choice A has wrong period π and wrong amplitude ½, C has wrong period π, and D has wrong amplitude 4. For trigonometric functions (sine and cosine): (1) Amplitude = |a| tells you how far from midline to peak (vertical stretch), (2) Period = 2π/|b| tells you how long one complete wave takes (horizontal compression if |b| > 1), (3) Midline y = d tells you the horizontal center (vertical shift). When b < 1 (like ½), the wave stretches horizontally, making the period longer than the standard 2π!

4

For the logarithmic function $f(x)=\log_5(x+1)$, what is the domain and the vertical asymptote?

Domain $x>-1$; vertical asymptote $x=-1$.

Domain $x\ge -1$; vertical asymptote $x=1$.

Domain $x>0$; vertical asymptote $x=0$.

Domain all real numbers; vertical asymptote $y=-1$.

Explanation

This question tests your ability to graph logarithmic functions by identifying their characteristic features like domain and asymptotes. Logarithmic functions f(x) = log_b(x) are the inverses of exponentials, so their graphs are reflections across y = x: they have an x-intercept at (1, 0) because log_b(1) = 0, no y-intercept because log_b(0) is undefined, and a vertical asymptote at x = 0 (the y-axis) that the graph approaches as x → 0⁺. The domain is restricted to x > 0 (can't take log of negative or zero), and end behavior is: as x → 0⁺, f(x) → -∞ (graph goes down along the asymptote), and as x → ∞, f(x) → ∞ (graph rises slowly, flattening as it goes). For f(x) = log₅(x + 1), the argument (x + 1) > 0 so domain x > -1, and vertical asymptote shifts left to x = -1 where the argument approaches 0 from right. Choice B correctly identifies domain x > -1 and vertical asymptote x = -1. A distractor like Choice A might ignore the shift and use standard log domain x > 0 with VA x=0, but transformations in the argument affect domain and asymptote. Exponential vs logarithmic graphing comparison: exponentials have y-intercept and horizontal asymptote (HA), while logarithms have x-intercept and vertical asymptote (VA). They're mirror images across y = x! Both never cross their asymptote. For exponentials, check the base: b > 1 means rising (growth), 0 < b < 1 means falling (decay). For logarithms, the graph always rises from left to right (slowly), hugging the VA on the left and flattening as it goes right. These characteristic shapes are instantly recognizable!

5

Identify the amplitude, period, and midline of the trigonometric function $f(x)= -3\sin(2x)+1$. (Relate to the parent function $y=\sin x$.)

Amplitude $3$; period $2\pi$; midline $y=-1$

Amplitude $3$; period $\pi$; midline $y=1$

Amplitude $-3$; period $\pi$; midline $y=1$

Amplitude $2$; period $\tfrac{2\pi}{3}$; midline $y=1$

Explanation

This question tests your ability to graph trigonometric functions by identifying their characteristic features like amplitude, period, and midline. Trigonometric functions like f(x) = a·sin(bx) + d have periodic (repeating) graphs with three key features: amplitude |a| is the vertical distance from the midline to a peak, period 2π/|b| is the horizontal length of one complete cycle, and midline y = d is the horizontal center line the graph oscillates around. The graph oscillates between y = d - |a| (minimum) and y = d + |a| (maximum), repeating this wave pattern every 2π/|b| units. For f(x) = 3sin(2x) + 1: amplitude 3, period π, midline y = 1, oscillating between -2 and 4. For f(x) = -3sin(2x) + 1, we identify: amplitude = |-3| = 3 (amplitude is always positive, representing distance), period = 2π/|2| = 2π/2 = π (the coefficient 2 compresses the wave horizontally), and midline y = 1 (from the +1 vertical shift). The negative sign flips the wave vertically but doesn't affect amplitude. Choice A correctly identifies amplitude 3, period π, and midline y = 1. Choice B incorrectly states amplitude as -3 (amplitude must be positive), while Choice C has the wrong period and midline. For trigonometric functions (sine and cosine): (1) Amplitude = |a| tells you how far from midline to peak (vertical stretch), (2) Period = 2π/|b| tells you how long one complete wave takes (horizontal compression if |b| > 1), (3) Midline y = d tells you the horizontal center (vertical shift). To sketch: draw the midline as a dashed horizontal line at y = d, mark one period length, sketch wave oscillating ±a from the midline. The negative sign in -3sin(2x) means the wave starts going down instead of up!

6

Sketch the logarithmic function $k(x)=\ln(x+2)$ showing the vertical asymptote and the x-intercept.

Vertical asymptote $x=0$; x-intercept $(1,0)$

Vertical asymptote $y=-2$; x-intercept $(-2,0)$

Vertical asymptote $x=-2$; x-intercept $(-1,0)$

Vertical asymptote $x=2$; x-intercept $(3,0)$

Explanation

This question tests your ability to graph logarithmic functions by identifying their characteristic features like asymptotes and intercepts. Logarithmic functions f(x) = log_b(x) are the inverses of exponentials, so their graphs are reflections across y = x: they have an x-intercept at (1, 0) because log_b(1) = 0, no y-intercept because log_b(0) is undefined, and a vertical asymptote at x = 0 (the y-axis) that the graph approaches as x → 0⁺. The domain is restricted to x > 0 (can't take log of negative or zero), and end behavior is: as x → 0⁺, f(x) → -∞ (graph goes down along the asymptote), and as x → ∞, f(x) → ∞ (graph rises slowly, flattening as it goes). For k(x) = ln(x+2), domain x+2>0 so x>-2, vertical asymptote at x=-2; x-intercept solves ln(x+2)=0 so $x+2=e^0$=1, x=-1, giving (-1,0). Choice C correctly identifies vertical asymptote x=-2 and x-intercept (-1,0). A distractor like choice A might use the basic ln(x) features without the +2 shift. Exponential vs logarithmic graphing comparison: exponentials have y-intercept and horizontal asymptote (HA), while logarithms have x-intercept and vertical asymptote (VA). They're mirror images across y = x! Both never cross their asymptote. For exponentials, check the base: b > 1 means rising (growth), 0 < b < 1 means falling (decay). For logarithms, the graph always rises from left to right (slowly), hugging the VA on the left and flattening as it goes right. These characteristic shapes are instantly recognizable!

7

For the logarithmic function $g(x)=\log_2(x-3)$, find the vertical asymptote and the x-intercept.

Vertical asymptote $y=3$; x-intercept $(3,0)$

Vertical asymptote $x=3$; x-intercept $(4,0)$

Vertical asymptote $x=0$; x-intercept $(1,0)$

Vertical asymptote $x=-3$; x-intercept $(-2,0)$

Explanation

This question tests your ability to graph logarithmic functions by identifying their characteristic features like intercepts and asymptotes. Logarithmic functions f(x) = log_b(x) are the inverses of exponentials, so their graphs are reflections across y = x: they have an x-intercept at (1, 0) because log_b(1) = 0, no y-intercept because log_b(0) is undefined, and a vertical asymptote at x = 0 (the y-axis) that the graph approaches as x → 0⁺. The domain is restricted to x > 0 (can't take log of negative or zero), and end behavior is: as x → 0⁺, f(x) → -∞ (graph goes down along the asymptote), and as x → ∞, f(x) → ∞ (graph rises slowly, flattening as it goes). For g(x) = log_2(x-3), the argument x-3 > 0 so domain x > 3, shifting the vertical asymptote to x=3; the x-intercept solves log_2(x-3)=0 so x-3=1, x=4, giving (4,0). Choice B correctly identifies the vertical asymptote x=3 and x-intercept (4,0). A distractor like choice A might ignore the horizontal shift, using the basic log features without the -3 adjustment. Exponential vs logarithmic graphing comparison: exponentials have y-intercept and horizontal asymptote (HA), while logarithms have x-intercept and vertical asymptote (VA). They're mirror images across y = x! Both never cross their asymptote. For exponentials, check the base: b > 1 means rising (growth), 0 < b < 1 means falling (decay). For logarithms, the graph always rises from left to right (slowly), hugging the VA on the left and flattening as it goes right. These characteristic shapes are instantly recognizable!

8

Identify the amplitude, period, and midline of the trigonometric function $p(x) = -2 \sin(3x) + 1$.

Amplitude $2$; period $\frac{2\pi}{3}$; midline $y=1$.

Amplitude $3$; period $\frac{2\pi}{3}$; midline $y=0$.

Amplitude $-2$; period $3\pi$; midline $y=1$.

Amplitude $2$; period $\frac{3\pi}{2}$; midline $y=-1$.

Explanation

This question tests your ability to graph trigonometric functions by identifying their characteristic features like period, amplitude, and midline. Trigonometric functions like $f(x) = a \sin(bx) + d$ have periodic (repeating) graphs with three key features: amplitude $|a|$ is the vertical distance from the midline to a peak, period $2\pi / |b|$ is the horizontal length of one complete cycle, and midline $y = d$ is the horizontal center line the graph oscillates around. The graph oscillates between $y = d - |a|$ (minimum) and $y = d + |a|$ (maximum), repeating this wave pattern every $2\pi / |b|$ units. For $f(x) = 3 \sin(2x) + 1$: amplitude 3, period $\pi$, midline $y = 1$, oscillating between -2 and 4. For $p(x) = -2 \sin(3x) + 1$, amplitude is $|-2| = 2$ (absolute value, so ignore the negative which flips the graph vertically), period is $2\pi / |3| = 2\pi/3$, midline is $y = 1$ (the +1 shifts it up). Choice A correctly identifies amplitude 2, period $2\pi/3$, and midline $y=1$. A distractor like Choice B might use the signed amplitude -2, but remember amplitude is always positive as it's a distance. For trigonometric functions (sine and cosine): (1) Amplitude = $|a|$ tells you how far from midline to peak (vertical stretch), (2) Period = $2\pi / |b|$ tells you how long one complete wave takes (horizontal compression if $|b| > 1$), (3) Midline $y = d$ tells you the horizontal center (vertical shift). To sketch: draw the midline as a dashed horizontal line at $y = d$, mark one period length, sketch wave oscillating $\pm a$ from the midline. Sine starts at midline going up, cosine starts at maximum. The wave repeats every period!

9

For the logarithmic function $r(x)=\log_5(x)$, which point is the x-intercept? (Use the parent log property $\log_b(1)=0$.)

$(0,1)$

$(0,5)$

$(1,0)$

$(5,0)$

Explanation

This question tests your ability to graph logarithmic functions by identifying their characteristic features like intercepts, asymptotes, and end behavior. Logarithmic functions f(x) = log_b(x) are the inverses of exponentials, so their graphs are reflections across y = x: they have an x-intercept at (1, 0) because log_b(1) = 0, no y-intercept because log_b(0) is undefined, and a vertical asymptote at x = 0 (the y-axis) that the graph approaches as x → 0⁺. The domain is restricted to x > 0 (can't take log of negative or zero), and end behavior is: as x → 0⁺, f(x) → -∞ (graph goes down along the asymptote), and as x → ∞, f(x) → ∞ (graph rises slowly, flattening as it goes). For r(x) = log₅(x), to find the x-intercept, we set r(x) = 0: log₅(x) = 0. This means x = 5⁰ = 1, so the x-intercept is (1, 0). Choice B correctly identifies this as (1, 0). Choice A reverses the coordinates (that would be a y-intercept, which logs don't have), C incorrectly uses the base as the x-value, and D also tries to give a y-intercept. Remember: ALL logarithmic functions of the form log_b(x) have their x-intercept at (1, 0) because log_b(1) = 0 for any base b!

10

On the same axes, sketch $f(x)=2^x$ and $g(x)=\log_2(x)$. Which statement correctly describes their relationship?

They are reflections of each other across the line $y=x$.

They are reflections of each other across the x-axis.

They have the same vertical asymptote.

They have the same y-intercept.

Explanation

This question tests your ability to graph exponential and logarithmic functions by identifying their characteristic relationship. Exponential functions f(x) = $ab^x$ have distinctive features: they have a y-intercept at (0, a) because b⁰ = 1, they never cross the x-axis (no x-intercepts for basic form), and they have a horizontal asymptote at y = 0 (the x-axis) that the graph approaches but never touches. End behavior depends on the base: if b > 1, it's exponential growth (left end approaches 0, right end goes to ∞); if 0 < b < 1, it's exponential decay (left end goes to ∞, right end approaches 0). Transformations like f(x) = $ab^x$ + k shift the horizontal asymptote to y = k! Logarithmic functions f(x) = log_b(x) are the inverses of exponentials, so their graphs are reflections across y = x: they have an x-intercept at (1, 0) because log_b(1) = 0, no y-intercept because log_b(0) is undefined, and a vertical asymptote at x = 0 (the y-axis) that the graph approaches as x → 0⁺. The domain is restricted to x > 0 (can't take log of negative or zero), and end behavior is: as x → 0⁺, f(x) → -∞ (graph goes down along the asymptote), and as x → ∞, f(x) → ∞ (graph rises slowly, flattening as it goes). For f(x) = $2^x$ and g(x) = log₂(x), since they are inverses $(log₂(2^x$) = x and $2^{log₂(x)}$ = x), their graphs are reflections across the line y = x; f has y-intercept (0,1) and HA y=0, g has x-intercept (1,0) and VA x=0. Choice B correctly states they are reflections across y = x. A distractor like Choice A might confuse with reflection over x-axis, but inverses reflect over y = x, swapping x and y. Exponential vs logarithmic graphing comparison: exponentials have y-intercept and horizontal asymptote (HA), while logarithms have x-intercept and vertical asymptote (VA). They're mirror images across y = x! Both never cross their asymptote. For exponentials, check the base: b > 1 means rising (growth), 0 < b < 1 means falling (decay). For logarithms, the graph always rises from left to right (slowly), hugging the VA on the left and flattening as it goes right. These characteristic shapes are instantly recognizable!

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