Chapter 4: Problem 77
For the following exercises, sketch the graph of each equation. $$ g(x)=-3 x+2 $$
Short Answer
Expert verified
The graph is a straight line with a slope of -3 and a y-intercept at (0, 2).
Step by step solution
01
Identify the Equation Type
The equation \(g(x) = -3x + 2\) is in the form of \(y = mx + b\), where \(m\) is the slope and \(b\) is the y-intercept. This is the equation of a straight line.
02
Determine the Slope and Y-Intercept
For \(g(x) = -3x + 2\), the slope \(m\) is -3, and the y-intercept \(b\) is 2. This means the line crosses the y-axis at the point (0, 2).
03
Plot the Y-Intercept
Start by plotting the y-intercept on the graph. Place a point on the y-axis at (0, 2).
04
Use the Slope to Find Another Point
The slope of -3 means that for every 1 unit you move to the right (positive direction along the x-axis), you move 3 units down (since -3 is negative) along the y-axis. From (0, 2), move 1 unit right to (1, 2) and 3 units down to (1, -1). Plot the point (1, -1).
05
Draw the Line
Connect the points (0, 2) and (1, -1) with a straight line. This line extends infinitely in both directions, following the slope of -3.
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Key Concepts
These are the key concepts you need to understand to accurately answer the question.
Slope
When discussing the equation of a line, slope refers to how steep or flat the line is. The slope can be found in the general line equation:
It's a key concept in graphing because it gives you a method to create the line once you have an initial point.
- In the formula \(y = mx + b\), \(m\) stands for slope.
- A positive slope means the line rises as you move from left to right, while a negative slope means it descends.
- For a slope of -3, it moves 3 units down for each unit it goes to the right.
It's a key concept in graphing because it gives you a method to create the line once you have an initial point.
Y-intercept
The y-intercept is where the line crosses the y-axis. In an equation like \(y = mx + b\), \(b\) is the y-intercept.
From this point, you can use the slope to determine how the line continues.
- This point is always found at \((0, b)\).
- For the equation \(g(x) = -3x + 2\), the y-intercept is 2, hence the line crosses the y-axis at the point \((0, 2)\).
From this point, you can use the slope to determine how the line continues.
Equation of a Line
The equation of a line in slope-intercept form is represented as \(y = mx + b\). This form clearly shows both the slope and the y-intercept, making it simpler to plot a line.
Having the equation in this form allows for quick graph sketching from just the slope and intercept values.
- \(m\) stands for slope, dictating the line's rise over run.
- \(b\) is the y-intercept, telling us where the line meets the y-axis.
Having the equation in this form allows for quick graph sketching from just the slope and intercept values.
Coordinate Plane
The coordinate plane is a two-dimensional surface where you can plot equations and points. It consists of two axes:
When graphing an equation like \(g(x) = -3x + 2\), understanding how the coordinate plane works helps you place each calculated point precisely. It's the stage where your equations come to life, as the relationship between x and y is plotted as a visual line or curve.
- The horizontal axis is the x-axis.
- The vertical axis is the y-axis.
When graphing an equation like \(g(x) = -3x + 2\), understanding how the coordinate plane works helps you place each calculated point precisely. It's the stage where your equations come to life, as the relationship between x and y is plotted as a visual line or curve.