Algebra 1

1
Algebra 1 Section 4.5 Quick Graphs Using
Slope-Intercept Form
Slope-Intercept form of the equation of a line y
mx b
m is the slope of the line
b is the y-intercept of the line
Find the slope and the y-intercept of the line.
y 3x 2
y - ½x - 5
slope y-intercept
- ½
slope y-intercept
3
-5
-2
2
Find the slope and y-intercept of the line.
1. y x
y 1x 0
2. 5x 7y 0
solve for y first to get in slope-intercept form
slope y-intercept
1
-5x -5x 7y -5x
-5 7
0
slope y-intercept
0
4. y 10 0
3. 3x 4y 12
solve for y first to get in slope-intercept form
solve for y
-10 -10 y -10
-3x -3x 4y -3x 12
slope y-intercept
0
-10
divide by 4
-3 4
slope y-intercept
3
3
Find the slope and the y-intercept of the line.
5. y - 4 (-8x)
6. x y 3x 4
get in slope-intercept form y mx b
solve for y
y - 4 8x y -8x 4
-x -x -y 2x 4 y -2x 4 divide
by - 1
slope y-intercept
-8
-2
slope y-intercept
- 4
- 4
7. 2x y 3 0
8. 2x 3y 4 x 5
solve for y
solve for y
y y y 2x - 3
-2x 4 -2x 4 3y -x 9

slope y-intercept
2
divide by 3
-3
-1 3
slope y-intercept
3
4
Find the slope and y-intercept, then graph the
line.
9. x y 0
solve for y
-x -x y -x

• to graph
• put a point on 0 on the y-axis (y-intercept)
• from there go down 1 and right 1 since slope is
  -1

-1
slope y-intercept
0
y
10. 3x 2y 2 0
solve for y
2y 2y 2y 3x 2
divide by 2
x
to graph -put a point on 1 on the y-axis
(y-intercept) - from there go up 3 and
right 2 since slope is 3/2
3 2
slope y-intercept
-1
5
Find the slope and y-intercept, then graph the
line.
11. y 3 0
-3 -3 y -3
to graph -put a point on 3 on the y-axis
(y-intercept) -from there the slope is 0, so it
is a horizontal line
slope y-intercept
0
-3
y
12. -x 1 -y 1
solve for y
-1 -1 -x 2 -y y
x 2 divide by -1
slope y-intercept
1
x
2
to graph -put a point on 2 on the y-axis -from
there, go up 1 and right 1
6
Two triangles are similar if their angles are
equal. Corresponding sides of similar triangles
have the same ratio.
actual
model
45 ft
10 ft
18 ft
x ft
To find the missing side on the model, use a
proportion
45 (actual) 18 (actual) 10 (model)
x (model)
45x 180 x 4 ft