Exam Review Q11

Has anyone gotten question 11 on the exam review?

I tried finding the critical points by finding partial derivatives and using the product rule treating xy as one term and (1-x-y) as the other. Solved for D = fxx * fyy - f^2xy and got a very long equation. It seemed like it got a lot more complicated than it was supposed to so I’m assuming I messed something up.

For God’s sake, don’t compute the discriminant D!!! It’s even worse with number 10. Again, the point is to use your computations in conjunction with the picture, which clearly indicates that the critical points are all saddle points. It also suggests that the critical points are at

You simply need to verify that those points do indeed solve system generated by the first derivatives.