Here's the problem
For each of the following functions, find the maximum and minimum values of the function on the rectanglar region: $−3≤x≤3,−4≤y≤4$. Do this by looking at level curves and gradiants.
I was able to solve the first two function, however I cannot find the right answer to the last function.
I first found
Then I equated these to $0$, resulting in $(x,y)=(0,0)$ and found
Thus, $D<0$ , thus we have a saddler point. So I'm very lost. I tried inputting $(0,0)$, but it's wrong.
I tried also in putting value $(-3,-4);(-3,4);(3,-4);(3,4)$ which all results into zero from the formula.
Can someone please explain what I am doing wrong?