Find All the Local Maxima, Local Minima, and Saddle Points $$f ( x , y ) = 81 x ^ { 2 } + 72 x y + 64 y ^ { 2 }$$

Multiple Choice

Find all the local maxima, local minima, and saddle points of the function.
- $$f ( x , y ) = 81 x ^ { 2 } + 72 x y + 64 y ^ { 2 }$$

A) f(9, 8) = 15,841, saddle point; f(8, 9) = 15,552, saddle point
B) f(72, 72) = 746,496, local maximum; f(0, 0) = 0, local minimum
C) f(0, 0) = 0, local minimum
D) f(72, 72) = 746,496, local maximum