00:01
We're solving the system of equations algebraically.
00:03
Top equation i have both x and y.
00:05
The bottom two have the first one has x and z, the last one y and z.
00:09
So i'm going to get rid of letter z, and i'm going to do that with elimination method.
00:13
So i'm going to multiply the second equation by four.
00:17
That'll give me a negative 12x plus 8 z equals 28.
00:25
The z's will go away.
00:27
You have a negative 12x plus 3y equals 33.
00:32
So i'm going to write down my top equation, my first equation, 2x plus y equals 5, and that new bottom equation that we just came up with.
00:45
And i'm going to get rid of the letter.
00:47
I'm going to get rid of the letter x just because my x's one line is positive once negative.
00:53
So multiply the top row by six to get a negative positive 12 there.
00:57
So you have 12x plus 6y equals 30.
01:03
Add those two equations together...