The Absolute Maximum Of $f ( x , y ) = 2 x + 2 y - x ^ { 2 } - y ^ { 2 } + 2$

Multiple Choice

The absolute maximum of $f ( x , y ) = 2 x + 2 y - x ^ { 2 } - y ^ { 2 } + 2$ on or inside the triangle with vertices (0, 0) , (9, 0) , and (0,9) is

A) 10
B) 8
C) 6
D) 4
E) 2