```Advanced Algebra Notes
Section 2.4: Write Equations of Lines
Given slope and y-intercept b
Use slope-intercept form
=  +
Given slope and a point (, )
Use point slope form
− 1 =   − 1
Given points (1 , 1 ) and (2 , 2 )
First use the slope formula to find m.
ℎ  ! Then use point-slope form with either point
()
()
=
ℎ ℎ   !
()
Example 1
Write an equation of the line shown.

=  +
ℎ   ? ℎ
ℎ ℎ   ℎ
− ?
3
=  + (−2)
4
Example 2
Write an equation of the line that passes through (5,4) and has a slope of −3.
− 1 = ( − 1 )
−
ℎ  !
− 4 = −3( − 5)
− 4 = −3( − 5)
− 4 = −3 + 15
= −3 + 19
Example 3
Write an equation of the line that passes through (−2,3) and is
Parallel to the line  = −4 + 1
ℎ   ℎ ℎ  !
= −4 +
−5 =
= −4 − 5
3 = −4(−2) +
Perpendicular to the line  = −4 + 1
ℎ   ℎ   !
1
1
− 1 = −4( − 1 )
1
7
= + +3
= +
1
4
2
4
2
− 3 = ( + 2)
4
Example 4
Write an equation of the line that passes through (5, −2) and (2,10)
ℎ !
10 − (−2)
=
2−5
12
=
−3
= −4
ℎ  !
− 1 = −4( − 1 )
ℎ   !
− (−2) = −4( − 5)
+ 2 = −4 + 20
= −4 + 18
Example 5
In the school year ending in 1993, 2.00 million females participated in U.S.
high school sports. By 2003, the number had increased to 2.86 million. Write
a linear equation that models female sports participation.
= #
= #
=  +
= (.086) +
ℎ  ℎ  ℎ  1993  2003
…  ℎ  … ℎ !
2.86 − 2.00
=
10 − 0
= .086
2.00  ℎ
= (.086) + 2.00
Closing: How do you write an equation of a line?
ℎ ,  −
ℎ
ℎℎ    …
−
=  +
−
− 1 = ( − 1 )
HOMEWORK
#1 − 19
```