Chapter 1: Problem 46
Identify any intercepts and test for symmetry. Then sketch the graph of the equation. $$y=2 x-3$$
Short Answer
Expert verified
The graph of the equation \(y = 2x-3\) has a y-intercept at -3 and x-intercept at 1.5. There is no symmetry. The graph is a straight line passing through points (1.5, 0) and (0, -3).
Step by step solution
01
Identify the Y-intercept
The y-intercept is the point on the graph where the line crosses the y-axis. This occurs when x=0. For the equation \(y=2x-3\), when x=0, \(y = -3\). So, the y-intercept is -3.
02
Identify the X-intercept
The x-intercept is the point on the graph where it crosses the x-axis. This happens when y=0. Set y=0 in the equation \(0=2x-3\), on solving we find that x = 3/2 or 1.5. This means the x-intercept is 1.5.
03
Test for Symmetry
Considering symmetry in the y-axis, when we replace \(x\) with \(-x\), if the equation remains the same then it shows symmetry. On replacement in the given equation, we get \(y = 2(-x) -3 = -2x - 3\), which is not the same as the original equation. So, the equation is not symmetric about the y-axis. Likewise, for symmetry in the origin, replace both \(x\) and \(y\) with \(-x\) and \(-y\) respectively. The equation should remain the same as the original equation, but in this case, -y = 2(-x) -3 turns into \(y = 2x + 3\), which again is not the same. Hence, the equation has no symmetry over the y-axis or the origin.
04
Sketch the Graph
Using the x and y intercepts plot (1.5, 0) and (0, -3) on the graph. Draw a line passing through these points which extends infinitely in both directions. The straight line represents the equation \(y = 2x - 3\).
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Key Concepts
These are the key concepts you need to understand to accurately answer the question.
Intercepts
In the context of a linear equation such as \(y=2x-3\), the intercepts are essential points where the graph of the line crosses the axes of the coordinate plane. Let's explore these intercepts:
- Y-intercept: This is the point where the line crosses the y-axis. To find the y-intercept, we set \(x=0\) in the equation. For our equation, substituting \(x = 0\) gives \(y = 2(0) - 3 = -3\). Therefore, the y-intercept is the point \((0, -3)\).
- X-intercept: This point is located where the line crosses the x-axis. To find the x-intercept, we set \(y=0\) in the equation. Substituting gives \(0 = 2x - 3\), solving this gives \(x = \frac{3}{2} = 1.5\). Therefore, the x-intercept is the point \((1.5, 0)\).
Linearity
The term "linearity" indicates that the relationship between the variables in the equation is consistent and direct, forming a straight line when graphed. This is an important feature of linear equations such as \(y = 2x - 3\). Here's why linearity is significant:
- Linear equations represent constant rates of change. For every unit increase in \(x\), there is a consistent increase or decrease in \(y\). In our equation, for every 1 unit increase in \(x\), \(y\) increases by 2 units, as shown by the coefficient of \(x\).
- The graph of a linear equation is always a straight line. This characteristic simplifies the process of graphing because only two points are needed to determine the entire line.
Graph Symmetry
Graph symmetry is about whether a graph is mirrored around an axis or a point. For the equation \(y=2x-3\), checking for symmetry helps us understand the graph's behavior:
- Y-axis Symmetry: A graph has y-axis symmetry if replacing \(x\) with \(-x\) in its equation results in the original equation. Substituting \(-x\) into our equation gives \(y = -2x - 3\). This is not the same as the original equation, so the graph is not symmetric around the y-axis.
- Origin Symmetry: A graph has origin symmetry if replacing both \(x\) with \(-x\) and \(y\) with \(-y\) leaves the equation unchanged. However, when we substitute in our equation, the result is \(-y = -2x - 3\), or equivalently \(y = 2x + 3\), which does not match the original. Thus, there is no symmetry about the origin either.