Notes with answers - Summit Schools

Your Notes
Example 2 Write an Equation Given Slope and a Point
Write an equation of the line that passes through (2, 1)
and has a slope of 2.
Solution
Because you know the slope and a point on the line,
use the point-slope form with (x1 , y1 ) 5 (2, 1) and
m 5 2 .
y 2 y1 5 m(x 2 x1 ) Use point-slope form.
y 2 1 5 2 (x 2 2 ) Substitute for m, x1 , and y1 .
Rewrite the equation in slope-intercept form.
y 2 1 5 2x 2 4 Distributive property
y 5 2x 2 3 Slope-intercept form
Checkpoint Write an equation of the line.
1. y
2. The line through (1, 5)
1
with a slope of 22
O
1
x
y 5 2
}
3 x 2 3 y 5 22x 1 7
Example 3 Write Equations of Parallel Lines
Write an equation of the line that passes through
(21, 1) and is parallel to the line y 5 22x 1 3.
Solution
The given line has a slope of 22 . Any line parallel
to this line must also have a slope of 22 . Use
point-slope form with (x1 , y1 ) 5 (21, 1) and
m 5 22 to write the equation of the line.
38 Lesson 2.5 • Algebra 2 C&S Notetaking Guide Copyright © McDougal Littell/Houghton Mifflin Company