00:01
For this problem, we are asked to show that the equation, z squared, or d squared, or d squared, or d squared, by d squared, x squared by d, y squared equals 0, is satisfied by z equals lon of root x squared plus y squared plus one half tan inverse of y over x.
00:16
Now, starting out with taking the partial derivative of, oops, partial derivative of, oops, taking the partial derivative of z with respect to x, now, lawn of root x squared plus y squared is going to require essentially two chains of applying chain rule.
00:34
So we'd have 1 over root x squared plus y squared times 1 over 2 root x squared plus y squared times 2x.
00:49
And then the 1 half 10 inverse of y over x would give us minus y over 2x squared times 1 plus y squared.
01:02
Squared over x squared...