I found two different approaches for solving this one. Still confused. What do you suggest to look for the first and then second derivative. Or anything else is on your mind. Please take a look. Thx a lot !

For each of the following functions, find the critical points and classify them as local

maximum, local minimum, saddle point, or "can't tell":a)xy^(2)+ x^(3)y − xy b) x^(2) − 6xy + 2y^(2) +10x + 2y −5