Chapter 4: Problem 16
Graph each function by making a table of coordinates. If applicable, use a graphing utility to confirm your hand-drawn graph. \(h(x)=\left(\frac{1}{3}\right)^{x}\)
Short Answer
Expert verified
The graph of the function \(h(x) = \left(\frac{1}{3}\right)^{x}\) is an exponential decay curve, decreasing from left to right. The points (-2, 9), (-1, 3), (0, 1), (1,1/3), and (2,1/9) are on the graph.
Step by step solution
01
Recognize the function
The function \(h(x)=\left(\frac{1}{3}\right)^{x}\) is an exponential function. The base of the exponential function is 1/3.
02
Create a table of values
This involves choosing some values for x and calculating the corresponding values for h(x), the function. Let's choose x values such as -2, -1, 0, 1, and 2. Substituting these x-values into the function; \n For x=-2, \(h(x)= \left(\frac{1}{3}\right)^{-2}= 9\);\n For x=-1, \(h(x)= \left(\frac{1}{3}\right)^{-1}= 3\);\n For x=0, \(h(x)= \left(\frac{1}{3}\right)^{0}= 1\);\n For x=1, \(h(x)=\left(\frac{1}{3}\right)^{1}= \frac{1}{3}\);\n For x=2, \(h(x)=\left(\frac{1}{3}\right)^{2}= \frac{1}{9}\).
03
Plot the points onto the graph
Take each (x, h(x)) pair from the table and plot it on a Cartesian plane. Connect the plotted points with a smooth curve. The points (-2, 9), (-1, 3), (0, 1), (1,1/3) and (2,1/9) should be on the curve.
04
Confirm the graph using a graphing utility
Input the function \(h(x) = \left(\frac{1}{3}\right)^{x}\) into a graphing calculator or online graphing tool to confirm the shape and points on the graph generated in Step 3.
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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 where the variable is in the exponent of a constant base. In our exercise, the function is \( h(x) = \left( \frac{1}{3} \right)^x \). This base of \( \frac{1}{3} \) is especially interesting because it is a fraction less than one, which means the function will decrease, or 'decay,' as \( x \) increases. An exponential decay function exhibits a rate of decline that becomes slower over time.
Some important characteristics of exponential functions include:
Some important characteristics of exponential functions include:
- The function value is never zero, but approaches zero asymptotically as \( x \) moves towards positive infinity.
- The y-intercept in this case is always \( h(0) = 1 \) because any base raised to the zero power equals one.
- The domain of these functions is all real numbers, while the range is all positive real numbers.
Table of values
Creating a table of values is a fundamental step in graphing any function. This process involves selecting a series of \( x \) values and calculating the corresponding \( h(x) \) values for our function. For our function \( h(x) = \left( \frac{1}{3} \right)^x \), we chose the values \( x = -2, -1, 0, 1, 2 \).
For each \( x \) value, we compute \( h(x) \):
For each \( x \) value, we compute \( h(x) \):
- When \( x = -2 \), \( h(x) = 9 \).
- When \( x = -1 \), \( h(x) = 3 \).
- When \( x = 0 \), \( h(x) = 1 \).
- When \( x = 1 \), \( h(x) = \frac{1}{3} \).
- When \( x = 2 \), \( h(x) = \frac{1}{9} \).
Graphing utility
A graphing utility is a tool, often a calculator or software, that can graph functions quickly and accurately. It is very handy for verifying your hand-drawn graphs. After plotting points manually, you can use graphing software to input \( h(x) = \left( \frac{1}{3} \right)^x \) and confirm the graph's shape and accuracy.
Using a graphing utility has several benefits:
Using a graphing utility has several benefits:
- Immediate visual feedback of your function's behavior across different \( x \) values.
- Accuracy in plotting, which can help you catch any errors in manual calculations.
- The ability to quickly test additional \( x \) values without recalculating everything manually.
Cartesian plane
The Cartesian plane is a two-dimensional coordinate system where you can plot points, lines, and curves to represent functions visually. It consists of a horizontal axis (x-axis) and a vertical axis (y-axis) that intersect at the origin, \( (0, 0) \).
When graphing \( h(x) = \left( \frac{1}{3} \right)^x \), each pair \( (x, h(x)) \) from our table of values corresponds to a point on this plane:
When graphing \( h(x) = \left( \frac{1}{3} \right)^x \), each pair \( (x, h(x)) \) from our table of values corresponds to a point on this plane:
- The point \( (-2, 9) \) shows how high the function value is when \( x \) is \(-2\).
- The point \( (0, 1) \) is the function’s y-intercept, where it crosses the y-axis.
- The points tend to get closer to the x-axis but never touch it as \( x \) increases, indicative of the asymptotic nature of exponential functions.