CH 13
How to Write an Equation of a Line y=mx+b
HP4L
Given the m &b
substute by m and b in the form y=mx+b
example: m = -1 b=3 y= -x+3
using a graph
find the y-intercept b
Find the slope... Rise/Run between 2 points
substitute by m and b in the form y=mx+b
If the line is going up the hill then m is + but if the line is going down the hill then m is -
Given two points
find m=y2- y1/x2-x1
find b by substiting m and one of the ordered pairs given
substitute by m&b in y=mx+b
example find the line that passes through points (2,-1) and (7,9)
m= 9-(-1)/7-2 = 10/5 = 2
find b
use (7,9)
9= (2)(7)+b
b=-14+9= -5
m=2 b= -5
y=2x-5
Example
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