the coefficient of x^2 is negative, so it is a downward opening parabola, it has a max.

this occurs at (6,5) -- do you see why?

the answer is my last responseb) For what value of x does the max or min occur?

since (x - 6)^2 is nonnegative, we have the max when we subtract as little as possible, that is, when (x - 6)^2 = 0