SOLUTION: How is the meeting point of two linear functions (equations) with differing slopes calculated. Thanks.

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Question 103152: How is the meeting point of two linear functions (equations) with differing slopes calculated.
Thanks.

Answer by Fombitz(32388) About Me  (Show Source):
You can put this solution on YOUR website!
Intersection of any two equations (linear or not) is handled by setting the equations equal to each other.
Here's an example.
1. y%5B1%5D=m%5B1%5Dx%2Bb%5B1%5D
2. y%5B2%5D=m%5B2%5Dx%2Bb%5B2%5D
The intersection would be where y%5B1%5D=y%5B2%5D.
y%5B1%5D=y%5B2%5D
m%5B1%5Dx%2Bb%5B1%5D=m%5B2%5Dx%2Bb%5B2%5D
You can then proceed to solve for x.
m%5B1%5Dx-m%5B2%5Dx%2Bb%5B1%5D=m%5B2%5Dx-m%5B2%5Dx%2Bb%5B2%5D
m%5B1%5Dx-m%5B2%5Dx%2Bb%5B1%5D-b%5B1%5D=b%5B2%5D-b%5B1%5D
%28m%5B1%5D-m%5B2%5D%29x=b%5B2%5D-b%5B1%5D
x%5Bi%5D=%28b%5B2%5D-b%5B1%5D%29%2F%28m%5B1%5D-m%5B2%5D%29
Once you have x, you can calculate y from (1) or (2) to get your intersection point.
Here's an example
y=2x%2B4
y=3x%2B5
x%5Bi%5D=%285-%284%29%29%2F%282-3%29
x%5Bi%5D=-1
y%5Bi%5D=2%28-1%29%2B4
y%5Bi%5D=2
The intersection point for this example is (-1,2).
+graph%28+300%2C+300%2C+-5%2C+5%2C+-5%2C+5%2C+2x%2B4%2C+3x%2B5%29+
Just as an interesting point, if the slopes of your lines were equal to each other, then your equation for x%5Bi%5D would fail because of division by zerom%5B1%5D-m%5B2%5D=0. In that case, since the slopes are equal, the lines never meet because they are parallel.