1. Lesson 6-4 Day 2 Slope Intercept Form
Objectives:
Students will be able to:
write equations using slope-intercept form.
identify slope and y-intercept from an equation.

2. b represents the y-intercept
Important!!!
This is one of the big concepts in Algebra 1. You need to thoroughly understand this!
Slope – Intercept Form
y = mx + b
m represents the slope
b represents the y-intercept

3. Writing Equations
When asked to write an equation, you need to know two things – slope (m) and y-intercept (b).

4. We have both!! Plug them into slope-intercept form
Writing Equations
Write an equation in slope-intercept form of the line that has a slope of 2 and a y- intercept of 6.
To write an equation, you need two things:
slope (m) =
y – intercept (b) =
We have both!! Plug them into slope-intercept form
y = mx + b 2 6
y = 2x + 6

5. y = -3x – 4 y = -4x – 3 y = -3x + 4 y = -4x + 3
Write the equation of a line that has a y-intercept of -3 and a slope of -4.
y = -3x – 4
y = -4x – 3
y = -3x + 4
y = -4x + 3

6. Graphing using Slope Intercept (y = mx + b)
 Put equation in slope intercept form
Plot the y-intercept
Use slope to find 2 more points

7. Graphing using Slope Intercept (y = mx + b)
b = -3 (y-intercept)
plot (0,-3)
y = 1/3 x - 3
m = 1/3 (slope rise/run)
positive leans right
plot up 1, right 3
plot down 1, left 3
connect the points

8. Graphing using Slope Intercept Form (y = mx + b)
b = 2 (y-intercept)
plot (0,2)
y = -1/2 x + 2
m = -1/2 (slope rise/run)
negative leans left
plot up 1, left 2
plot down 1, right 2
connect the points

9. Find the slope and y-intercept. y = 3x – 7 y = mx + b m = 3, b = -7
To find the slope and y-intercept of an equation, write the equation in slope-intercept form: y = mx + b.
Find the slope and y-intercept.
y = 3x – 7
y = mx + b
m = 3, b = -7

10. Find the slope and y-intercept.
2) y = x
y = mx + b
y = x + 0
3) y = 5
y = 0x + 5
m =
b = 0
m = 0
b = 5

11. Find the slope and y-intercept. 4) 5x - 3y = 6
Write it in slope-intercept form. (y = mx + b)
5x – 3y = 6
-3y = -5x + 6 -3 -3 -3
m =
b = -2
y = x - 2

12. Find the slope and y-intercept. 5) 2y + 2 = 4x
Write it in slope-intercept form. (y = mx + b)
2y + 2 = 4x
2y = 4x - 2 2 2 2
m = 2
b = -1
y = 2x - 1

13. Find the slope and y-intercept of y = -2x + 4
m = 2; b = 4
m = 4; b = 2
m = -2; b = 4
m = 4; b = -2

14. Homework: p # 28 – 39 all