Finding maximum and minimum value

[rainwyz0706]

Homework Statement

We have x^2+y^2+z^2=1, and we want to find the maximum and minimum value of xz+xy-yz.

Homework Equations

The Attempt at a Solution

I've simplified the original problem to this point, but I'm not sure what to do next. Could anyone give me some hints? Any help is greatly appreciated!

 

[vela]

Try using Lagrange multipliers.

http://en.wikipedia.org/wiki/Lagrange_multipliers

 

[rainwyz0706]

Thanks a lot! I finished it already:p