Slope - Intercept Form of the equation will help us to find the equation
given two points.
y = mx + b

STep 1. Find the slope given two points.
y2-y1
Slope or m = ______________
x2-x1

(4, 5) = (x1, y1)
(12,8) = (x2,y2 )

m = 12-4/8-5
m= 8/3

Step 3 : Find the y - intercept or b
y = mx + b where m = 8/3, x= 4, y = 7

Note : you can use either of the two points given. same slope of course
7 = 8/3(4) + b
7 = 32/3 + b
32/3 - 7 = b
32/3 -21/3 = b
11/3=b

Substitute m = 8/3, b = 13 to slope -intercept form y = mx + b
y = 8/3x + 11/3 ---> this is the equation in slope -intercept form
8/3x - y = 11/3 ----> Equation in standard form.

Oct 10th, 2014

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