00:01
So i want to solve this three variable system.
00:05
And these can get a little bit messy because there's a bunch of things we have to do.
00:11
So let's see, i'm going to start off by taking that first equation and i'm going to rewrite it so that it says z equals.
00:20
So in other words, i'm going to subtract x from both sides.
00:28
Next i'm going to go to my second equation that has a z in it and i'm going to replace that z with 6 minus x.
00:46
Okay.
00:47
And i'm just going to move things around here so that my equation equals y.
00:55
So i'm going to add 3y to both sides and subtract 7 and then i'm just going to divide everything by 3.
01:04
So now i have an equation that says y equals, right? y equals 6 minus x minus 7 over 3.
01:23
You can keep cleaning that up because that's another way of saying negative x minus 1 over 3.
01:32
So now look what i've got.
01:33
I've got a y equals and a z equals.
01:37
So i'm going to take both of them now to this third equation and substitute them.
01:43
I'm going to keep the x term, but instead of y, i'm going to say that's plus negative x minus 1 over 3.
01:55
And instead of 3z, i'm going to say 3, 6 minus x, because that's what z equals, and together, altogether, that's going to be 15...