Chapter 10: Problem 75
In the following exercises, graph each exponential function. $$ f(x)=(0.4)^{x} $$
Short Answer
Expert verified
Plot points (-2, 6.25), (-1, 2.5), (0, 1), (1, 0.4), and (2, 0.16) and connect them with a smooth curve.
Step by step solution
01
Identify Key Points
To graph the function, start by identifying key points. Choose a few values for \( x \) and calculate corresponding \( y \) values for \( f(x) = (0.4)^{x} \). For example, let \( x \) be -2, -1, 0, 1, and 2.
02
Calculate Y-values
Compute the values for the function at chosen points: \[ f(-2) = (0.4)^{-2} = \frac{1}{(0.4)^{2}} \ f(-1) = (0.4)^{-1} = \frac{1}{0.4} \ f(0) = (0.4)^{0} = 1 \ f(1) = (0.4)^{1} = 0.4 \ f(2) = (0.4)^{2} = 0.16 \]
03
Plot the Points
Using the points calculated, plot them on a coordinate grid. The points are (-2, 6.25), (-1, 2.5), (0, 1), (1, 0.4), and (2, 0.16).
04
Draw the Graph
Connect the plotted points with a smooth curve. The curve should approach the horizontal axis (x-axis) as \( x \) increases but will never touch it. The graph will also rise steeply for negative values of \( x \).
05
Analyze the Graph's Behavior
Note that the exponential function \( f(x)=(0.4)^{x} \) is decreasing since the base of the exponent (0.4) is between 0 and 1. The y-values will get closer to 0 as x increases.
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Key Concepts
These are the key concepts you need to understand to accurately answer the question.
Exponential Functions
Exponential functions are a type of mathematical function involving an exponent. The basic form of an exponential function is given by \( f(x) = a^{x} \), where \( a \) is a constant called the base and \( x \) is the variable. In this exercise, the base is 0.4.
An important trait of exponential functions is how they grow or decay:
An important trait of exponential functions is how they grow or decay:
- If \( a > 1 \), the function experiences exponential growth.
- If \( 0 < a < 1 \), there is exponential decay, as in our example with 0.4.
Plotting Points
To graph exponential functions, start by plotting points. This involves choosing specific values for \( x \) and computing the corresponding \( y \) values called \( f(x) \).
Follow these steps:
Follow these steps:
- Choose a range of values for \( x \). In our case, we chose \( x = -2, -1, 0, 1, \) and \( 2 \).
- Calculate the \( y \)-values using the given function. For \( f(x) = (0.4)^{x} \):
\( f(-2) = (0.4)^{-2} = \frac{1}{(0.4)^{2}} = 6.25 \)
\( f(-1) = (0.4)^{-1} = \frac{1}{0.4} = 2.5 \)
\( f(0) = (0.4)^{0} = 1 \)
\( f(1) = (0.4)^{1} = 0.4 \)
\( f(2) = (0.4)^{2} = 0.16 \)
Graph Analysis
After plotting these points, you can start drawing the actual graph.
Some important aspects to keep in mind while doing graph analysis include:
Some important aspects to keep in mind while doing graph analysis include:
- Connecting the plotted points using a smooth curve. The curve should not be broken or jagged.
- Observing how the graph behaves as \( x \) increases or decreases. For \( f(x) = (0.4)^{x} \), the graph approaches the x-axis but never touches it.
- Noting how the graph rises steeply for negative values of \( x \) since exponential decay reverses for negative exponents.
Function Behavior
Understanding the behavior of exponential functions helps in visualizing and graphing them effectively.
For the function \( f(x) = (0.4)^{x} \), the following behaviors are observed:
For the function \( f(x) = (0.4)^{x} \), the following behaviors are observed:
- The function is decreasing because the base 0.4 is between 0 and 1. This results in exponential decay.
- As \( x \) increases, the \( y \)-values get closer to 0, but the function never actually touches the x-axis. This is known as an asymptote.
- For negative values of \( x \), the function values increase steeply, reflecting the reciprocal relationship in the exponentiation.