00:01
This first thing i'm going to do is write down the first two equations.
00:03
I've got 2x plus y equals 6, and i have 3y minus 2 z equals negative 4.
00:28
So what i want to try and do here, just get rid of my y terms.
00:34
And how i'm going to do that is i'm going to multiply the top equation times a negative 3.
00:40
And then add them together.
00:43
So that would give me a negative 6x, and there's no x terms.
00:47
I'm going to leave that here.
00:51
Then my y term would go away, and then i'd have 2z equals.
00:59
This would give me a negative 18 on the top, and negative 4 on the bottom, so i'd have a negative 20.
01:08
Now that seemed like an odd thing to do, but the next thing i'm going to be able to do now is use my other equation, which is 3x minus 5 z equals negative 7.
01:26
So i'm going to do a couple of things here.
01:29
I'm actually going to take this equation now and multiply it times 2.
01:36
We'll rewrite the other clear.
01:37
So it will be times 2.
01:40
So now i'm going to write that down here...