Let $f ( x , y ) = a x ^ { 2 } + b x - y ^ { 2 } + c y + d$

True/False

Let $f ( x , y ) = a x ^ { 2 } + b x - y ^ { 2 } + c y + d$ , for constants a, b, c, and d, with $a \neq 0$ .
The constants can be chosen in such a way that f will have a local minimum.