## Calculus with Applications (10th Edition)

The theorem on location of extrema suggests that for a function $z=f(x,y)$, suppose all points (a,b) where $f_{x}(a,b)=0$ and $f_{y}(a,b)=0$. Then by testing each of the points separately, we can conclude whether there is a relative maximum, or a relative minimum or a saddle point at $(a,b)$