Chapter 1: Problem 9
Determine all intercepts of the graph of the equation. Then decide whether the graph is symmetric with respect to the \(x\) axis, the \(y\) axis, or the origin. $$ y=x-\frac{1}{x} $$
Short Answer
Expert verified
x-intercepts are at (1,0) and (-1,0); there is no symmetry.
Step by step solution
01
Find the x-intercept
The x-intercept is the point where the graph intersects the x-axis. For this, set the equation equal to zero and solve for x: \[ 0 = x - \frac{1}{x} \] Multiply both sides by x to eliminate the fraction: \[ 0 = x^2 - 1 \] This is a difference of squares, which factors to: \[ (x-1)(x+1) = 0 \] So, the solutions are \( x = 1 \) and \( x = -1 \). The x-intercepts are at the points (1,0) and (-1,0).
02
Find the y-intercept
The y-intercept occurs where the graph intersects the y-axis, which is when \( x = 0 \). Substitute 0 for x in the equation: \[ y = 0 - \frac{1}{0} \] However, this expression is undefined due to division by zero. Thus, there is no y-intercept for the graph.
03
Test symmetry with respect to the x-axis
A graph is symmetric with respect to the x-axis if replacing y with -y yields an equivalent equation. Substitute \( -y \) for y: \[ -y = x - \frac{1}{x} \] This new equation is not equivalent to the original equation \( y = x - \frac{1}{x} \), so the graph is not symmetric with respect to the x-axis.
04
Test symmetry with respect to the y-axis
A graph is symmetric with respect to the y-axis if replacing x with -x yields an equivalent equation. Substitute \( -x \) for x: \[ y = -x + \frac{1}{-x} \] Simplifying the second term gives: \[ y = -x - \frac{1}{x} \] This is not equivalent to the original equation \( y = x - \frac{1}{x} \), so the graph is not symmetric with respect to the y-axis.
05
Test 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. Substitute \( -x \) for x and \( -y \) for y: \[ -y = -x - \frac{1}{x} \] Multiplying both sides by -1 gives: \[ y = x + \frac{1}{x} \] This is clearly not equivalent to the original equation \( y = x - \frac{1}{x} \), so 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 the X-Intercept
The x-intercept is a vital point on a graph where it crosses the x-axis. This means the value of y is 0 at this point. To find the x-intercept, you set the equation equal to zero.
This involves calculating where the graph intersects the x-axis by solving the equation:
This involves calculating where the graph intersects the x-axis by solving the equation:
- Start with the equation: \( 0 = x - \frac{1}{x} \)
- Multiply through by \( x \) to eliminate the fraction: \( 0 = x^2 - 1 \)
- This is a difference of squares, represented as \( (x-1)(x+1) = 0 \)
- Solving gives you \( x = 1 \) and \( x = -1 \)
Exploring the Y-Intercept
The y-intercept is where a graph crosses the y-axis. For this point, the value of x is zero. You find it by substituting 0 for x in the equation.
However, with this specific equation, when you plug in zero for x:
However, with this specific equation, when you plug in zero for x:
- The equation becomes: \( y = 0 - \frac{1}{0} \)
- Division by zero is undefined, which means there is no y-intercept for this graph.
Discovering Graph Symmetry
Symmetry in graphs can make them easier to interpret. It means that a graph looks the same on different sides of an axis or origin.
There are types of symmetry to check for:
There are types of symmetry to check for:
- X-Axis Symmetry: Replacing y with -y
\(-y = x - \frac{1}{x}\) is not equivalent to the original, so no x-axis symmetry. - Y-Axis Symmetry: Replacing x with -x
\ y = -x - \frac{1}{x}\ is not equivalent; thus, no y-axis symmetry. - Origin Symmetry: Replacing x and y with -x and -y
\ -y = -x - \frac{1}{x}\ simplifies to \ y = x + \frac{1}{x}\, which is not equivalent.