00:01
Okay, we want to take the derivative implicitly.
00:04
So i'm going to change this to 2x to the minus 1 minus y to the minus 1 equals 4.
00:13
So the derivative would be minus 2 x to the minus 2 plus y to the minus 2 equals 0.
00:23
Oh, bad me.
00:25
I forgot.
00:26
The derivative of x is 1, but the derivative of y is y prime.
00:31
That was weird.
00:34
All right.
00:36
So the derivative minus 2x to the minus 2 times the derivative of x, which is 1, and then this minus and minus 1 makes plus, y to the minus 2 times the derivative of y, and that's equal to 0.
00:54
All right, so y to the minus 2, y prime equals 2x to the minus 2, or y prime over y squared equals 2 over x squared.
01:11
So y prime is 2 y squared over x squared.
01:19
All right.
01:20
Now i'm going to solve that equation for y and then take the derivative that way.
01:30
Okay, so there's lots of things you could do, but i'm just going to do what i always do.
01:35
I don't like fractions to work with.
01:38
So i'm going to multiply by xy to get rid of them.
01:41
So i have 2y minus x equals 4xy...