Can you please explain, not sure what I keep doing wrong. Thank you.

Find the local maximum and minimum values and saddle point(s) of the function. If you have three-dimensional graphing software, graph the function with a domain and viewpoint that reveal all the important aspects of the function. (Enter your answers as a comma- separated list. If an answer does not exist, enter DNE.) f(x, y) = 2x3 + xy2 + 5x2 + 12+ 7 local maximum value(s) X local minimum value(s) (-1, 4) X saddle point(s) ( x , y, f ) = Submit Answer Viewing Saved Work Revert to Last Response [-/1.25 Points] DETAILS SCALCET8 14.7.508.XP. MY NOTES Find the local maximum and minimum values and saddle point(s) of the function. If you have three-dimensional graphing software, graph the function with a domain and viewpoint that reveal all the important aspects of the function. (Enter your answers as a comma- separated list. If an answer does not exist, enter DNE.) F( x, y) = x4 + y4- 4xy+ 5 local maximum value(s) local minimum value(s) saddle point(s) ( x , y, f ) =