Chapter 1: Problem 58
Find any intercepts of the graph of the given equation. Determine whether the graph of the equation possesses symmetry with respect to the \(x\) -axis, \(y\) -axis, or origin. Do not graph. \(y=\frac{x^{2}-10}{x^{2}+10}\)
Short Answer
Expert verified
X-intercepts: \((\sqrt{10}, 0), (-\sqrt{10}, 0)\); Y-intercept: \((0, -1)\). Symmetric w.r.t. y-axis.
Step by step solution
01
Find the x-intercepts
To find the x-intercepts, set the equation equal to zero and solve for \(x\): \(y = \frac{x^2 - 10}{x^2 + 10} = 0\). This equation is equal to zero when the numerator is equal to zero, provided the denominator is not zero. Therefore, \(x^2 - 10 = 0\). Solving for \(x\), we get \(x^2 = 10\) or \(x = \pm \sqrt{10}\). Thus, the x-intercepts are at \((\sqrt{10}, 0)\) and \((-\sqrt{10}, 0)\).
02
Check for y-intercept
To find the y-intercept, set \(x = 0\) and solve for \(y\): \(y = \frac{(0)^2 - 10}{(0)^2 + 10} = \frac{-10}{10} = -1\). Thus, the y-intercept is at \((0, -1)\).
03
Test for symmetry with respect to the x-axis
A graph is symmetric with respect to the x-axis if replacing \(y\) with \(-y\) in the equation yields an equivalent equation. Testing: \(-y = \frac{x^2 - 10}{x^2 + 10}\). Solving for \(y\), we get \(y = -\frac{x^2 - 10}{x^2 + 10}\), which is not equivalent to the original equation. Therefore, the graph is not symmetric with respect to the x-axis.
04
Test for symmetry with respect to the y-axis
A graph is symmetric with respect to the y-axis if replacing \(x\) with \(-x\) in the equation yields an equivalent equation. Testing: \(y = \frac{(-x)^2 - 10}{(-x)^2 + 10} = \frac{x^2 - 10}{x^2 + 10}\). Since the equation is unchanged, the graph is symmetric with respect to the y-axis.
05
Test for symmetry with respect to the origin
A graph is symmetric with respect to the origin if replacing \(x\) with \(-x\) and \(y\) with \(-y\) yields an equivalent equation. Testing: \(-y = \frac{(-x)^2 - 10}{(-x)^2 + 10} = \frac{x^2 - 10}{x^2 + 10}\). Solving for \(y\), \(y = -\frac{x^2 - 10}{x^2 + 10}\), which is not equivalent to the original equation. Thus, the graph is not symmetric with respect to the origin.
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Key Concepts
These are the key concepts you need to understand to accurately answer the question.
Understanding x-intercepts
The concept of an x-intercept is quite straightforward. It's where the graph of an equation crosses the x-axis. In mathematical terms, this happens when the value of y is zero. Finding the x-intercepts of an equation involves setting the y to zero and solving for x.
For the equation given, the task was to solve \( y = \frac{x^2 - 10}{x^2 + 10} = 0 \). By making the numerator zero (as a fraction is zero only when its numerator is zero), we got \(x^2 - 10 = 0\). Solving this gives \(x = \pm \sqrt{10}\).
So, the graph crosses the x-axis at two points: \( (\sqrt{10}, 0) \) and \( (-\sqrt{10}, 0) \). Always remember:
For the equation given, the task was to solve \( y = \frac{x^2 - 10}{x^2 + 10} = 0 \). By making the numerator zero (as a fraction is zero only when its numerator is zero), we got \(x^2 - 10 = 0\). Solving this gives \(x = \pm \sqrt{10}\).
So, the graph crosses the x-axis at two points: \( (\sqrt{10}, 0) \) and \( (-\sqrt{10}, 0) \). Always remember:
- X-intercepts happen when \( y = 0 \).
- Set the numerator to zero when dealing with rational functions to find x-intercepts.
Exploring y-intercepts
Y-intercepts are where the graph meets the y-axis. Finding them is simpler than x-intercepts. All you need to do is set \(x = 0\) in the equation and solve for y. It tells you where the graph crosses the y-axis.
For the given equation, substituting \(x = 0\) resulted in \( y = \frac{(0)^2 - 10}{(0)^2 + 10} = \frac{-10}{10} = -1 \). It means the y-intercept is at the point \( (0, -1) \).
To sum up:
For the given equation, substituting \(x = 0\) resulted in \( y = \frac{(0)^2 - 10}{(0)^2 + 10} = \frac{-10}{10} = -1 \). It means the y-intercept is at the point \( (0, -1) \).
To sum up:
- Set \( x = 0 \) to find the y-intercept.
- The y-intercept is where the graph intersects the y-axis.
Delving into symmetry
Symmetry in graphs can help you understand the nature of a function's graph, simplifying how you think about its shape and behavior. There are three main types of symmetry you might consider:
- Symmetry with respect to the x-axis: This happens when replacing \(y\) with \(-y\) gives the same equation. Our example didn't have this symmetry, as evidenced when we tested it.
- Symmetry with respect to the y-axis: Occurs if by replacing \(x\) with \(-x\), you get an equivalent equation. For the equation in question, this symmetry existed because replacing \(x\) with \(-x\) did not change the equation: \( y = \frac{x^2 - 10}{x^2 + 10} \).
- Origin symmetry: This symmetry appears when swapping both \(x\) with \(-x\) and \(y\) with \(-y\) results in the same equation. In our case, the graph wasn't symmetric with the origin since that substitution altered the equation.
- Graphs symmetric about the y-axis are mirror images across the y-axis.
- Graphs symmetric about the x-axis are mirror images across the x-axis, and for symmetric about the origin graphs, rotating 180 degrees results in the same graph.