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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
slope = 3
y-intercept = -2
y = - ½x - 5
slope = - ½
y-intercept = -5
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Find the slope and y-intercept of the line.
1. y = x
y = 1x + 0
slope = 1
y-intercept = 0
3. 3x + 4y = 12
-3x
-3x
4y = -3x + 12
3
y   x 3
4
slope = -3
4
y-intercept = 3
solve for y first to get
in slope-intercept form
2. 5x + 7y = 0
-5x
-5x
7y = -5x
5
y x
7
4. y + 10 = 0
solve for y first to get
in slope-intercept form
slope = -5
7
y-intercept = 0
solve for y
-10 -10
y = -10
slope = 0
y-intercept = -10
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Find the slope and the y-intercept of the line.
5. y = - 4 + (-8x)
y = - 4 – 8x
y = -8x – 4
get in slope-intercept form
y = mx + b
+y
+y
y = 2x - 3
slope = 2
y-intercept = -3
-x
solve for y
-x
-y = 2x + 4
y = -2x – 4 divide by - 1
slope = -2
y-intercept = - 4
slope = -8
y-intercept = - 4
7. 2x – y – 3 = 0
6. x – y = 3x + 4
solve for y
8. 2x + 3y – 4 = x + 5
-2x
solve for y
+4 -2x +4
3y = -x + 9
1
y   x 3
3
slope = -1
3
y-intercept = 3
divide by 3
© Mr. Sims
Find the slope and y-intercept, then graph the line.
9. x – y = 0
-x
-x
solve for y
-y = -x
y=x
slope = 1
y-intercept = 0
to graph
-put a point on 0 on the y-axis (y-intercept)
-from there go up 1 and right 1 since slope is 1
10. 3x – 2y – 2 = 0
+2y
solve for y
y
+2y
2y = 3x – 2
3
y  x  1 divide by 2
2 to graph
-put a point on –1 on the
slope = 3
y-axis (y-intercept)
2
- from there go up 3
y-intercept = -1 and right 2 since slope
x
is 3/2
© Mr. Sims
Find the slope and y-intercept, then graph the line.
11. y + 3 = 0
-3
-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
y = -3
slope = 0
y-intercept = -3
12. -x – 1 = -y + 1
-1
-x – 2 = -y
y=x+2
solve for y
y
-1
divide by -1
slope = 1
y-intercept = 2
x
to graph
-put a point on 2 on the y-axis
-from there, go up 1 and right 1
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Mr. Sims
Sims
©
Two triangles are similar if their angles are equal.
Corresponding sides of similar triangles have the same ratio.
45 ft
10 ft
actual
model
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
© Mr. Sims
Algebra 1
Section 4.5
Assignment
Find the slope and y-intercept of the line.
1.) y = 3x – 6
2.) y = 4x – 20
3.) 2y – x = 7x – 9
Write the equation in slope-intercept form.
4.) x – y + 2 = 0
5.) x – y = 0
6.) 3x – 2y – 2 = 0
7.) 10x + 6y – 3 = 0
8.) y + 5 = 0
9.) -x + 4y + 3 = 2x – 7
© Mr. Sims
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