00:01
So i'm going to go ahead and solve this system of linear equations.
00:04
I've got four equations and i've got four different variables.
00:09
I have a w, x, y, and z.
00:14
So we've got a couple of different things going on here.
00:17
The first equation we've got is x plus 3w is equal to 4.
00:22
So i'm probably going to go ahead and just rewrite that as 4 minus 3w.
00:28
So that'll be equation number one.
00:30
Equation number two looks like we've got 2y minus z minus w is equal to zero.
00:38
I'm going to isolate that z.
00:41
I'll add the z to the other side.
00:44
Z is equal to 2y minus w.
00:49
Now i could have isolated the w.
00:51
I just chose to do the z.
00:52
We'll see if that helps.
00:54
It may or may not.
00:56
We'll see what happens.
00:57
And then i've got a third equation.
01:00
I've got 3y minus 2w equals 1.
01:05
That's already set up sort of like when we would do a two variable system.
01:09
So i'm not going to isolate a variable there.
01:10
It doesn't seem like i need to.
01:12
And then equation 4 looks like i've got what starts as 2x minus y plus 4z equals 5.
01:23
I probably would rewrite that with y equals.
01:30
Isolate the y there.
01:32
Looks like we're probably going to need to substitute some stuff in there with the x and the z.
01:39
So let's just leave that as 2x minus y plus 4z equals 5.
01:44
And let's see what substitution will do for us.
01:49
So what i'm going to do is i'm going to leave equation 3 just as it is, but i'm going to take equations 1 and 2, which have an x and a z.
01:59
And i'm going to go ahead and plug them in for x and z in equation 4, and then simplify that and see what i got.
02:07
So i've got 2 times 4 minus 3 w minus y plus 4 times 2 w minus y, and that's equal to 5.
02:18
Let's simplify this.
02:20
We get 8 minus 6w minus y plus 8 y minus 8 w minus 8 w.
02:29
And it looks like when we combine like terms, we're going to get 7y.
02:35
I'm sorry, this is not an 8...