Chapter 2: Problem 59
Sketch the graph of the equation. Identify any intercepts and test for symmetry. \(y=5-3 x\)
Short Answer
Expert verified
The graph of the equation \(y=5-3x\) is a straight line with a negative slope. It crosses the y-axis at (0,5) and the x-axis at approximately (\(\frac{5}{3}\),0). The graph doesn't show any symmetry.
Step by step solution
01
Sketch the Graph
Start by identifying the y-intercept which is the constant term, 5. This is the point where the line crosses the y-axis. So we have the point (0,5). The slope of the line (which is -3) tells us that for each positive step along the x-axis, we go three steps negatively along the y-axis. Draw a straight line through these points which will represent the equation \(y=5-3x\).
02
Identify the Intercepts
The y-intercept is already found at point (0,5). To find the x-intercept(s), set y equal to 0 and solve for x. So, \(0=5-3x\) gives \(x=\frac{5}{3}\) or approximately 1.67. So, the x-intercept is at the point (\(\frac{5}{3}\),0).
03
Test for Symmetry
A function is symmetric about the y-axis if replacing \(x\) with \(-x\) results in the same function, and it's symmetric about the origin if that replacement yields the negative of the original function. Replace \(x\) with \(-x\) in the equation. The equation becomes \(y=5-(-3x) = 5+3x\), which is not the same as the original function. So, the graph has no symmetry about the y-axis or the origin.
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Key Concepts
These are the key concepts you need to understand to accurately answer the question.
Graph Sketching
When sketching the graph of a linear equation, such as \( y = 5 - 3x \), we begin by identifying crucial points like intercepts, and then drawing the line defined by the equation. Linear equations result in straight lines. Thus, having a few key points is usually enough to define the graph.
- Identify the Intercepts: We'll start by finding the y-intercept and x-intercepts (if any). These points help us accurately plot the line on a graph.
- Understanding the Slope: The equation \( y = 5 - 3x \) reveals a slope of \(-3\). This means as you move 1 unit right (positive direction on the x-axis), the line will drop 3 units down (negative direction on the y-axis), creating a line that slants downward from left to right.
- Plotting and Drawing: Begin plotting from the y-intercept at (0,5). Move according to the slope until at least two points are set. Connect these points with a straight line to represent the equation.
Intercepts
Intercepts are critical points where the graph intersects the axes. Specifically, we'll look at:
- Y-intercept: This is where the line crosses the y-axis. In the equation \( y = 5 - 3x \), the constant term, \(5\), indicates that the y-intercept is at the point (0,5).
- X-intercept: Found by setting \(y = 0\) and solving for \(x\). Substituting into our equation, we get \(0 = 5 - 3x\). Solving for \(x\), we find the x-intercept at \(x = \frac{5}{3}\) or approximately 1.67, making the x-intercept at (\(\frac{5}{3}\), 0).
Slope
The slope of a linear equation like \( y = 5 - 3x \) is a measure of how steep the line is. In simple terms, it tells us how much \( y \) increases or decreases as \( x \) increases by one unit.
- Understanding Slope: With the equation in the form \( y = mx + b \), \(m\) is the slope. Here, \(m = -3\).
- Interpreting \(-3\): This slope means for every unit step to the right on the x-axis, the line drops 3 steps. It is negative, indicating a downward slant from left to right.
- Practical Use: Start from the y-intercept (0,5), then use the slope: move 1 unit to the right, and 3 units down to locate the next point.
Symmetry
Symmetry in the context of graphing refers to whether a graph can be reflected across an axis or around a point without changing appearance.
- Y-axis Symmetry: A graph has symmetry about the y-axis if replacing \(x\) with \(-x\) yields the same equation. For \( y = 5 - 3x \), replacing \(x\) with \(-x\) results in \( y = 5 + 3x \), which changes the equation, indicating no y-axis symmetry.
- Origin Symmetry: Symmetry about the origin requires that replacing \(x\) with \(-x\) and \(y\) with \(-y\) results in the same equation. Using our equation, it becomes \(-y = 5 + 3x\) after necessary changes, which isn't equivalent to the original.