Writing the Equation of a Line

Review of Slope-Intercept Form

The slope-intercept form of a linear equation is

y = mx + b.

m represents the slope

b represents the y-intercept

Write the Equation in Slope-Intercept Form

5. The slope is 2; the y-intercept is 5

6. The slope is -4; the y-intercept is 0

7. The slope is - ; the y-intercept is -3

8. The slope is ; the y-intercept is 71

21

34

y = 2x + 5

y = -4x

y = - x – 321

1. Find the Equation of the LineGiven the Slope and y-intercept

m = -3, b = 1

m = -2, b = -4

m = 0, b = 10

m = 1, b = 0

m = 0, b = 0

●Substitute m and b into y = mx + b

y = -3x + 1

y = -2x - 4

y = 0x + 10, y = 10

y = 1x + 0, y = x

y = 0x + 0, y = 0

Given the slope and y-intercept, write the equation of a line in slope-intercept form.

1) m = 3, b = -14

2) m = -½, b = 4

3) m = -3, b = -7

4) m = 1/2 , b = 0

5) m = 2, b = 4

Slope-intercept form of an equation

Y = mx + b

Example 1

●b = -3

●m =

●y = x - 3

3

2

x

y

+2

+33

2

Example 2

●b = 1

●m =

●y = x + 1

1

2

x

y

+1-2

1

2

Example 3

●b = 4

●m = 0/1= 0

●y = 0x + 4, y = 4

x

y

Write an Equation in Slope-Intercept Form

10. Write the Equation for this line

Slope = m =

y-intercept = b

223

xy

3

22

3

= -2

Write an Equation in Slope-Intercept Form

11. Write the Equation for this line

Slope = m =

y-intercept = b

345

xy

5

44

5

= 3

Write an Equation in Slope-Intercept Form

12. Write the Equation for this line

Slope = m =

y-intercept = b

12 xy

2

4

= -22

4

= 1