Chapter 2: Problem 41
19–44 ? Make a table of values and sketch the graph of the equation. Find the x- and y-intercepts and test for symmetry. $$ x=y^{3} $$
Short Answer
Expert verified
Graph is symmetric about the origin with x- and y-intercepts at (0,0).
Step by step solution
01
Make a Table of Values
To create a table of values, choose several values for \( y \) and compute the corresponding \( x \) using the equation \( x = y^3 \). For example:- If \( y = -2 \), then \( x = (-2)^3 = -8 \).- If \( y = -1 \), then \( x = (-1)^3 = -1 \).- If \( y = 0 \), then \( x = 0^3 = 0 \).- If \( y = 1 \), then \( x = 1^3 = 1 \).- If \( y = 2 \), then \( x = 2^3 = 8 \).The table now looks like:| \( y \) | \( x = y^3 \) ||:---:|:---:|| -2 | -8 || -1 | -1 || 0 | 0 || 1 | 1 || 2 | 8 |
02
Sketch the Graph
Using the table of values, plot the points on the graph. Connect them to see the curve:- Plot (-8, -2), (-1, -1), (0, 0), (1, 1), and (8, 2) on a coordinate plane.- The graph forms a cubic curve which is consistent with the equation \( x = y^3 \).
03
Find the x- and y-intercepts
To find where the curve intersects the axes:- **x-intercept:** It's where the graph crosses the x-axis, which occurs when \( y = 0 \). For \( y = 0 \), \( x = 0^3 = 0 \). Therefore, the x-intercept is at (0, 0).- **y-intercept:** It's where the graph crosses the y-axis, which occurs when \( x = 0 \). For \( x = 0 \), \( y = 0 \) since \( y^3 = 0 \). Therefore, the y-intercept is at (0, 0).
04
Test for Symmetry
Test the equation for symmetry by replacing variables and observing if the resulting equation is equivalent to the original:- **Symmetry about the x-axis:** Replace \( y \) with \( -y \): the equation becomes \( x = (-y)^3 = -y^3 \) which is not equivalent to \( x = y^3 \). Not symmetric about x-axis.- **Symmetry about the y-axis:** Replace \( x \) with \( -x \): the equation becomes \( -x = y^3 \), which is not equivalent. Not symmetric about y-axis.- **Symmetry about the origin:** Replace \( x \) with \( -x \) and \( y \) with \( -y \): the equation becomes \( -x = (-y)^3 = -y^3 \), equivalent. Symmetric about the origin.
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Key Concepts
These are the key concepts you need to understand to accurately answer the question.
X-Intercepts
An x-intercept is a point where a graph crosses the x-axis. This happens when the value of y is zero. For the equation \( x = y^3 \), we set \( y = 0 \) to find the x-intercept. By substituting \( y = 0 \) into the equation, we get:\[x = 0^3 = 0\]So, the x-intercept for this cubic function is at the point \((0, 0)\).
- Key takeaway: An x-intercept tells us where the graph meets the x-axis. In this case, it happens because when \( y \) is zero, \( x \) also becomes zero.
- It's useful to note that in some functions, there may be more than one x-intercept depending on the degree and shape of the polynomial.
Y-Intercepts
The y-intercept is the point where the graph crosses the y-axis. This occurs when the value of \( x \) is zero. By setting \( x = 0 \) in the equation \( x = y^3 \), we solve for \( y \):\[0 = y^3\]The solution to this equation is \( y = 0 \), which means that the y-intercept for the curve is also at \((0, 0)\).
- Key insight: A y-intercept gives us the point where a curve meets the y-axis.
- Like the x-intercept, the y-intercept of this function is the origin. This indicates that both the x and y intercepts coincide in this case.
Symmetry in Graphs
Symmetry in graphs provides insights into the balance and structure of a curve. For the equation \( x = y^3 \), we are particularly interested in three types of symmetry: x-axis, y-axis, and origin.
**Symmetry about the x-axis**: We test this by replacing \( y \) with \( -y \). The equation becomes \( x = (-y)^3 = -y^3 \). Since this new equation is not the same as the original, the graph is not symmetric about the x-axis.
**Symmetry about the y-axis**: For this test, replace \( x \) with \( -x \), resulting in \( -x = y^3 \). As this is not equivalent to \( x = y^3 \), the graph does not exhibit symmetry about the y-axis.
**Symmetry about the origin**: Here, replace both \( x \) with \( -x \) and \( y \) with \( -y \). This gives us \( -x = (-y)^3 = -y^3 \). This equation is equivalent to the original, indicating that the graph is symmetric about the origin.
**Symmetry about the x-axis**: We test this by replacing \( y \) with \( -y \). The equation becomes \( x = (-y)^3 = -y^3 \). Since this new equation is not the same as the original, the graph is not symmetric about the x-axis.
**Symmetry about the y-axis**: For this test, replace \( x \) with \( -x \), resulting in \( -x = y^3 \). As this is not equivalent to \( x = y^3 \), the graph does not exhibit symmetry about the y-axis.
**Symmetry about the origin**: Here, replace both \( x \) with \( -x \) and \( y \) with \( -y \). This gives us \( -x = (-y)^3 = -y^3 \). This equation is equivalent to the original, indicating that the graph is symmetric about the origin.
- Conclusion: Symmetry about the origin suggests a balanced nature around the center of the graph, here the origin point \((0, 0)\).
- This type of symmetry helps in understanding how the graph might look when we rotate it 180 degrees around the origin.