00:01
Okay, we're given this function of two variables.
00:03
We want to examine the critical points.
00:07
So first let's find them.
00:08
To do that, we take the first partial derivatives.
00:12
Fx is this, and fy is this.
00:22
Okay.
00:24
So to find the critical points, we set fx and fy equal to zero.
00:31
So let's add the two of them together.
00:35
Because when we do that, these first couple terms are going to cancel out.
00:40
And then the rest of them will be able to work with.
00:46
So we add them together, fxx plus fx plus fy, gives us this.
00:54
So that tells us that either x is plus y or minus y.
01:03
So if x equals y, we plug it back into one of these equations, and we get that 36 equals x squared.
01:14
Oops.
01:18
So x is plus or minus six...