1. 13.7 – Writing Linear Equations
What does the m represent?
What does the b represent?
y=mx+b
SLOPE!!!
Y-INT!!! Y
Name the slope and y-intercept of each line
m b
BLUE
GREEN
PURPLE

2. We are going to learn how to write equations.
There are three main types.
1) Slope and y-intercept
2) Slope and a point
3) Two points

4. Y - I N T = 3 m = 1 y = 1 x + 3

5. Solve for y, change it to ‘y =‘
Distribute
Get y by itself

6. We are going to learn how to write equations.
There are three main types.
1) Slope and y-intercept
2) Slope and a point
3) Two points

7. Writing an equation given a slope and a point.
Point-slope form
Slope-intercept form
Plug in the slope and the point into point slope form
Plug in the slope and the point into point slope form
Solve for y (get y by itself) 2 3 1 –6

8. Slope-intercept form Point-slope form Standard form 1 2 4 2
Write the equation of the line given a point and a slope in point-slope form 1 2 2 4

9. Slope-intercept form Point-slope form Standard form 1 2 4 2
Write the equation of the line given a point and a slope in SLOPE-INTERCEPT FORM 1 2 2 4

10. Find points and label Find points and label Plug into formula
y2 – y1
SLOPE = m =
x2 – x1
Find points and label
Plug into formula
Reduce Fraction
(3,-1) (2, 3)
x1 y1 x2 y2
Find points and label
Plug into formula
Reduce Fraction
(0, 2) (2, -4)
x1 y1 x2 y2 y2 3 y1 -1 -4 y2 y1 2 x2 x2 x1 2 x1 3 2 4 -6 -1 2

11. We are going to learn how to write equations.
There are three main types.
1) Slope and y-intercept
2) Slope and a point
3) Two points
One new thing:
Find your own darn slope!
ADJ:AJDSAK:JFDS:FJIJOWEJC:DSJK:FJKOWEIJFKSD:EJIFLSJFKSLFJSKFLJSFELIWPOWPJDPWAOJLJFSLSDEFPWOPEFJSLKFJWPEJFSDLFJSLOPEDSJFKL:WJPAFJPDSVOJDSPKFEIWLPJFKLSDFJ:AJWPVDSNFELWKGJWLEGIJLRIJGDFI

12. 3) Change into correct form -4 3 2
Slope-intercept form
y2 – y1
m =
Point-slope form
x2 – x1
Standard form
1) Find slope
2) Take slope, ANY POINT
3) Change into correct form
(3,-1) (2, 3)
x1 y1 x2 y2 3 y2 y1 -1 x2 2 x1 3 4 -1 -4 3 2
Slope-int

13. 3) Change into correct form -1 2 1 –4
Slope-intercept form
y2 – y1
m =
Point-slope form
x2 – x1
Standard form
1) Find slope
2) Take slope, ANY POINT
3) Change into correct form -4 y2 y1 1
(-4,1) (6, -4)
x1 y1 x2 y2 -1 2 x2 6 -4 x1 1 –4 -5 10
Slope-int

14. 3) Change into correct form 1 3 5
Slope-intercept form
y2 – y1
m =
Point-slope form
x2 – x1
Standard form
1) Find slope
2) Take slope, ANY POINT
3) Change into correct form 7 y2 y1 5
(0,5) (6, 7)
x1 y1 x2 y2 1 3 x2 6 x1 5 2 6
Standard

15. Practice problems
Slope – Int Standard
(3, 4); (1, 2) (-2, 4) (1, -5)

16. HW #55: Pg 555: 8, 10, 17 – 20 (slope-int and standard) 22, 23, 25 – 30 (even standard, odd slope-intercept), 33 – 38. (20 problems, end problems not easy)
Hint for 33, think circumcenter.