Question 400208: How do I find the equation of the line joining the following pairs of points:
1. (1,8) and (-1,-20)
2. (2,-1) and (3,5)
Answer by lwsshak3(11628)   (Show Source):
You can put this solution on YOUR website! How do I find the equation of the line joining the following pairs of points:
1. (1,8) and (-1,-20)
2. (2,-1) and (3,5)
..
These equations can take one of two forms: slope-intercept or point-slope. I will do the former, y=mx+b, m being the slope and b the y-intercept. The problem is to find the slope,m, and the y-intercept,b.
1. slope=change in y/change in x or rise/run.
=8-(-20)/1-(-1)=28/2=14
y=14x+b
using first ordered pair(1,8) (using either pair is ok)
8=14(1)+b
b=8-14=-6
equation: y=14x-6
..
2. slope=change in y/change in x or rise/run.
=(-1-5)/(2-3)=-6/-1=6
y=6x+b
using first ordered pair(2,-1) (using either pair is ok)
-1=6(2)+b
b=-12-1=-13
equation: y=6x-13
See these two equations on the graph below:
..
|
|
|
