1. Writing Equations in Slope-Intercept form
5.2

2. Three Easy Steps Step 1: Identify Slope
Use slope formula if you know two points
Step 2: Identify the y-intercept
Plug the slope and one point into the equation y = mx + b, then solve for b
Step 3: Write the equation
Y = mx + b, insert m and b

3. Given Slope and Point
Write an equation of the line that passes through the point (6,3) and has a slope of 2.
Step 1
Step 2
Step 3
Y = 2x +b
3 = 2(6) + b
-9 = b
Y = 2x - 9

4. Try it out
Write an equation of the line that passes through the point (6,3) and has a slope of -2.
Y = -2x + 15

5. Given Two Points
Write an equation of the line that passes through the points (1,-2) and (-5,4).
Step 1
Step 2
Step 3
Y = -x + b
M = y2 – y1 = 4 – (-2) = -1
x2 – x – (1)
4 = -(-5) + b
-1 = b
Y = -x - 1

6. Try it out
Write an equation of the line that passes through (3,0) and (2, -4)
Not the y-intercept… what is it?
Y = 4x - 12

7. Real-World Problem
A carnival charges $2.50 per ride after an entrance fee. You paid a total of $22.50 after 6 rides. Write an equation that gives the total cost as a function of the number of rides.
What do we know?
M = and (6, 22.5)

8. Continued Step 1 Step 2 Step 3 Y = 2.5x + b 22.5 = 2.5(6) + b -15 -15
7.5 = b
What does this tell us?
Y = 2.5x + 7.5