Find all relative extrema and saddle points of the function. Use the Second Partials Test where applicable. (If an answer does not exist, enter DNE.) f(x, y) = 2xy - (x + y) +8 relative minimum (x, y, z) = relative maxima (x, y, z) = (smaller x-value) (x, y, z) = = (larger x-value) saddle point (x, y, z) = 5 5 -10 -5 6 5 10