Chapter 1: Problem 41
In Problems \(41-66\), 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. \(y=-3 x\)
Short Answer
Expert verified
The intercept is at (0,0), and the graph is symmetric with respect to the origin.
Step by step solution
01
Finding the x-intercept
An x-intercept is a point where the graph intersects the x-axis. At this point, the value of y is 0. To find the x-intercept, set y = 0 and solve the equation.\[0 = -3x\]Solving for x gives:\[x = 0\]So, the x-intercept is at the point (0,0).
02
Finding the y-intercept
A y-intercept is a point where the graph intersects the y-axis. At this point, the value of x is 0. To find the y-intercept, set x = 0 and use the equation.\[y=-3(0)\]This simplifies to:\[y = 0\]So, the y-intercept is at the point (0,0).
03
Testing for symmetry with respect to the x-axis
For a graph to be symmetric with respect to the x-axis, replacing y with -y in the equation should yield an equivalent equation. Start with the equation:\[y = -3x\]Replacing y with -y gives:\[-y = -3x\]Multiplying the whole equation by -1 results in:\[y = 3x\]Since this is not equivalent to the original equation, the graph is not symmetric with respect to the x-axis.
04
Testing for symmetry with respect to the y-axis
For a graph to be symmetric with respect to the y-axis, replacing x with -x in the equation should yield an equivalent equation. Start with the equation:\[y = -3x\]Replacing x with -x gives:\[y = -3(-x)\]This simplifies to:\[y = 3x\]Since this is not equivalent to the original equation, the graph is not symmetric with respect to the y-axis.
05
Testing for symmetry with respect to the origin
For a graph to be symmetric with respect to the origin, replacing both x with -x and y with -y should yield an equivalent equation. Start with the equation:\[y = -3x\]Replace x with -x and y with -y:\[-y = -3(-x)\]This simplifies to:\[-y = 3x\]Multiplying the whole equation by -1 yields:\[y = -3x\]Since this results in the original equation, the graph is 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 of a graph is where it crosses the x-axis. At this point, the value of y is 0. Let's see how that works: if you set y to 0 in the equation, you're solving for the point where it hits the x-axis. For the equation \( y = -3x \), substituting y with 0 gives us:
Understanding x-intercepts can help in graph analysis and predict where other intercepts might be based on the graph's behavior.
- \[ 0 = -3x \]
- Solving this, we find that \( x = 0 \)
Understanding x-intercepts can help in graph analysis and predict where other intercepts might be based on the graph's behavior.
Exploring the Y-Intercept
The y-intercept is the point where the graph crosses the y-axis. Here, the value of x is 0. By setting x to 0, we can find this precise location on the graph. Looking at the equation \( y = -3x \) and substituting x with 0:
This intercept is particularly useful for finding initial starting points when sketching a graph as it shows where the graph starts from the y-axis.
- \[ y = -3(0) \]
- y simplifies to 0
This intercept is particularly useful for finding initial starting points when sketching a graph as it shows where the graph starts from the y-axis.
Investigating Graph Symmetry
Graph symmetry helps us understand balance in a graph's appearance. There are three main types of symmetry to consider: with respect to the x-axis, y-axis, and origin.
Understanding symmetry can simplify graphing and better predict graph behavior around key axes changes.
- X-Axis Symmetry: Replacing y with -y in the original equation does not result in the same equation (\( y = 3x \)). Hence, there's no symmetry about the x-axis.
- Y-Axis Symmetry: Replacing x with -x gives us \( y = 3x \), which also is not the same as the original. Thus, the graph is not symmetric about the y-axis.
- Origin Symmetry: Replacing both x and y with their negatives, \(-y = 3x\), can be rearranged to return to the original equation, \( y = -3x \). This confirms symmetry about the origin.
Understanding symmetry can simplify graphing and better predict graph behavior around key axes changes.