Examine the function for relative extrema and saddle points. (if an answer does not exist, enter dne.) h(x, y) = x2 − 9xy − y2

The given function is
h(x,y) = x² - 9xy - y²

Calculate partial derivatives.

For the critical points,


To perform a test for a saddle point, calculate

Because D < 0, a saddle point exists at (0,0).