Download Graphing Lines Using Slope-Intercept Form

4.7
Graphing Lines Using
Slope-Intercept Form
Goal
Graph a linear equation
in slope-intercept form.
How can you estimate production costs?
In Example 3 you will use the
graph of a linear model to estimate
the production costs for a small
hat-making business.
Key Words
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slope
y-intercept
slope-intercept form
parallel lines
In Lesson 4.5 you learned to find the slope of a line given two points on the line.
There is also a method for finding the slope given an equation of a line.
SLOPE-INTERCEPT FORM OF THE EQUATION OF A LINE
The linear equation y mx b is written in slope-intercept form,
where m is the slope and b is the y-intercept.
slope
y-intercept
y mx b
If y 2x 3, then (0, 3) and (1, 5) are on the line
and the slope is 2. More generally, if y mx b,
then (0, b) and (1, m b) are on the line and the
(m b) b
10
slope is m.
y
(1, 5)
(0, 3)
y 2x 3
1
3
EXAMPLE
1
1
3 x
Find the Slope and y-Intercept
Find the slope and y-intercept of 2x y 3.
Solution Rewrite the equation in slope-intercept form.
2x y 3
Write original equation.
y 2x 3
Subtract 2x from each side.
y 2x 3
ANSWER 䊳
Divide each side by 1. m 2 and b 3.
The slope is 2. The y-intercept is 3.
4.7
Graphing Lines Using Slope-Intercept Form
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