Find the maximum value of 8x - x^2 + 7x - 2x^2, for real numbers x.
Rearrange as
-3x^2 + 15x
The max value occurs when x = -(15) / (2 * -3) = -15 / -6 = 5/2 = 2.5
And the max is
-3 (2.5)^2 + 15 (2.5) =
18.75