1. 4.4 Writing Linear Equations
What is the y-intercept?
b = -1
What is the slope?
m = 2
Use y = mx + b form
to write equation.
y = 2x -1

2. y = mx + b 7 = 3(2) + b 7 = 6 + b 1 = b y = 3x + 1
Given: m = 3 and it goes through (2,7)
write the equation of the line.
y = mx + b
7 = 3(2) + b
Plug the slope and the point in to the equation.
7 = 6 + b
1 = b
y = 3x + 1
Plug the slope and b back in.

3. You try this one
Given: m = -2 and it goes through (1,6) write the equation of the line.
y = -2x + 8

4. Given two points, write an equation.
(3,2) and (-4,9)
First, find slope. m=
y = mx + b
Use one of the points and the slope to find b.
2 = -1(3) + b 1st point is used (3,2)
2 = -3 + b Simplify
5 = b
y = -1x + 5
Plug the slope and b back in.

5. Write an equation given 2 points.
Given (3,4) and(-2,7) write an equation.
First find the slope.
Then pick a point
Plug it in and solve for b.
Write the equation in slope-intercept form with the m and b you just found.

6. If you pick the other point it works too!
Given (3,4) and(-2,7) write an equation.
First find the slope.
Then pick a point
Plug it in and solve for b.
Write the equation in slope-intercept form with the m and b you just found.

7. You try this one!
Given points (2,1) and (0,-3) find the equation of the line.
y = 2x -3

8. Linear Extrapolation
When you use a linear equation to predict values that are beyond the range of the data.
Try this one: Illia and her friends rented a canoe for 3 hours and paid a total of $45. Canoe rentals: Daily rate plus $10 per hour.
Write a linear equation to find the total cost C of renting the canoe for h hours.
C = 10h + 15
How much would it cost to rent the canoe for 8 hours?
$95