00:01
Let's solve the following system of equations.
00:02
And we want to do this by eliminating variables.
00:05
And i see automatically that i need to eliminate that y because there is no y value in this third equation.
00:11
I'm also going to number my equation so i remember what i'm doing.
00:15
So i'm going to say 1 plus 2.
00:17
So that's going to be x plus y plus z equals to 0.
00:22
2x minus y plus 3 z equals to 0.
00:25
So that tells me that 3x plus 4 z equals to 0.
00:32
I can now combine that with equation 3 because i have only the variables x and z.
00:38
So i'm going to come over here and say 3x plus 4 z equals to 6 and x minus z equals to, i'm sorry, that's equal to 0 equals to 6.
00:50
So what i'm going to do is take this bottom equation and multiply it by 4 to create the, this same coefficient but opposites.
00:59
So that's going to be 3x plus 4z equals to 0.
01:03
4x minus 4z equals to 24.
01:07
So that's going to give me 7x equals to 24.
01:12
Dividing by 7, i'm going to have x equals 24 over 7.
01:17
Now we have a yucky number, but we'll have to deal with it...