00:02
All right, so my system here says that we have x plus 2y equals 0, negative 2x plus 4y plus 8z equals 8, and 3x minus 3z equals negative 9.
00:29
So a couple of options here, depending on which way you want to go with that.
00:34
I'm going to work with the first two and eliminate y to get an equation with x and z to go with the third equation.
00:42
So i'm going to take x plus 2y equals 0 and negative 2x plus 4y plus 8z equals 8.
00:56
Now my coefficients don't line up, so i'm going to take my top equation and i'm going to multiply it by negative 2.
01:03
So when that happens, i'm going to get negative 2x minus 4y equals 0.
01:14
Now i didn't touch the second one, so i'm just going to bring it down.
01:17
Negative 2x plus 4y plus 8 z equals 8.
01:28
Now when i add those together, i'm going to get negative 4x.
01:33
This is going to cancel plus 8z equals 8.
01:38
This can now be paired with this equation to eliminate either x or z.
01:47
We have 3x minus 3z equals negative 9.
01:54
And then our combo equation here, negative 4x plus 8z equals 8.
02:01
Now neither one of those have the same coefficients, so we're going to do some multiplication...