# Find the Slope and Y-Intercept (1,-9) , (9,-13) (1,-9) , (9,-13)
Find the value of the slope.
Slope is equal to the change in y over the change in x, or rise over run.
m=change in ychange in x
The change in x is equal to the difference in x-coordinates (also called run), and the change in y is equal to the difference in y-coordinates (also called rise).
m=y2-y1x2-x1
Substitute in the values of x and y into the equation to find the slope.
m=-13-(-9)9-(1)
Simplify.
Simplify the numerator.
Multiply -1 by -9.
m=-13+99-(1)
m=-49-(1)
m=-49-(1)
Simplify the denominator.
Multiply -1 by 1.
m=-49-1
Subtract 1 from 9.
m=-48
m=-48
Reduce the expression by cancelling the common factors.
Cancel the common factor of -4 and 8.
Factor 4 out of -4.
m=4(-1)8
Cancel the common factors.
Factor 4 out of 8.
m=4⋅-14⋅2
Cancel the common factor.
m=4⋅-14⋅2
Rewrite the expression.
m=-12
m=-12
m=-12
Move the negative in front of the fraction.
m=-12
m=-12
m=-12
m=-12
Find the value of the y-intercept.
Substitute the value of m into the slope-intercept form of the equation, y=mx+b.
y=(-12)⋅x+b
Substitute the value of x into the slope-intercept form of the equation, y=mx+b.
y=(-12)⋅(1)+b
Substitute the value of y into the slope-intercept form of the equation, y=mx+b.
-9=(-12)⋅(1)+b
Rewrite the equation as (-12)⋅(1)+b=-9.
(-12)⋅(1)+b=-9
Multiply -1 by 1.
-12+b=-9
Move all terms not containing b to the right side of the equation.
Add 12 to both sides of the equation.
b=-9+12
To write -9 as a fraction with a common denominator, multiply by 22.
b=-9⋅22+12
Combine -9 and 22.
b=-9⋅22+12
Combine the numerators over the common denominator.
b=-9⋅2+12
Simplify the numerator.
Multiply -9 by 2.
b=-18+12
b=-172
b=-172
Move the negative in front of the fraction.
b=-172
b=-172
b=-172
The values of the slope and y-intercept are m=-12 and b=-172.
m=-12
b=-172
Find the Slope and Y-Intercept (1,-9) , (9,-13)     