Chapter 1: Problem 20
Graph each of the functions without using a grapher. Then support your answer with a grapher. $$ y=5^{-x^{2}} $$
Short Answer
Expert verified
The graph of \(y = 5^{-x^2}\) is a symmetric curve with key point (0,1) and asymptote at \(y = 0\).
Step by step solution
01
Identify the General Form
The function given is \( y = 5^{-x^2} \). This is an exponential function where the base is 5 and the exponent is \(-x^2\). The negative sign in the exponent suggests that this is a decreasing function as \(x\) moves away from zero in either direction.
02
Determine Key Points
To graph the function, identify key points. When \( x = 0 \), \( y = 5^{0} = 1 \). As \(x\) increases or decreases from zero, the value of \(-x^2\) becomes more negative, making \(5^{-x^2}\) approach zero. Calculate additional points such as \(x = 1\) and \(x = -1\) to find that \(y = 5^{-1} \approx 0.2\).
03
Analyze Symmetry and Asymptotes
Since \(x^2\) is even, the function is symmetric about the y-axis. The exponential factor means there is a horizontal asymptote at \(y = 0\), as the function never touches the x-axis.
04
Sketch the Graph
Plot the determined key points: \((0, 1)\), \((1, 0.2)\), \((-1, 0.2)\), and note the symmetry. Draw a smooth, continuous curve, decreasing towards the asymptote \(y = 0\) as \(|x|\) increases.
05
Verify with Graphing Tool
Use a graphing calculator or software to graph \(y = 5^{-x^2}\) and verify the manually-drawn graph matches. Check that key points and the shape of the graph align with your sketch.
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Key Concepts
These are the key concepts you need to understand to accurately answer the question.
Graphing Techniques
To graph exponential functions like \( y = 5^{-x^2} \), start by understanding its general behavior. This function represents exponential decay since the exponent is negative. Follow these basic steps to depict the graph accurately.
- Identify the general form and base. Here, the base is 5, and it is raised to the power of \(-x^2\).
- Notice the direction. As the power is negative, the graph will show a decay pattern, decreasing as \( |x| \) increases.
- Plot key points. Begin with the essential point where \( x = 0 \), resulting in \( y = 1 \).
Symmetry in Functions
Symmetry is a crucial aspect when graphing functions. In the function \( y = 5^{-x^2} \), the exponent \( -x^2 \) is even. This indicates that the function is symmetric about the y-axis.
Here's why that symmetry occurs:
Here's why that symmetry occurs:
- For any positive value of \( x \), the same value of \( -x \) will produce the same \( y \).
- The even power \( x^2 \) ensures equality in the absolute value of \( x \) on both sides of the y-axis.
Asymptotes
In exponential functions, especially those approaching zero, asymptotes play a crucial role. For \( y = 5^{-x^2} \), a horizontal asymptote exists at \( y = 0 \).
- As \( x \) becomes larger in positive or negative direction, \( y = 5^{-x^2} \) approaches zero but will never reach it.
- The asymptote is a guideline that shows the direction of the graph as it stretches towards infinity.
Key Points in Graphing
Identifying key points is essential for accurately sketching a function. For \( y = 5^{-x^2} \), pinpoint certain values of \( x \) to see how \( y \) changes.
- Start with \( x = 0 \). At this point, \( y = 1 \).
- Try \( x = 1 \) and \( x = -1 \). Both give \( y \approx 0.2 \), demonstrating symmetry.
- Test further points like \( x = 2 \) and \( x = -2 \), where \( y \) becomes even smaller (around \( y \approx 0.04 \)).