If x is real, find the maximum value of the expression -2x^2 + 11x + 13. Choices:  A) 16.125  B) 20.125  C) 24.125  D) 28.125  E) 32.125
This is an equation of a downward facing parabola.   The maximum value is the top point of the parabola.   -2x^2+11x+13 = (-2x+13)(x+1)   The roots are 13/2 and -1.   The maximum value must be when x is halfway between these two points.   x = 2.75   The maximum value is -2(2.75)^2+11(2.75)+13 = 28.125   The answer is 28.125.
<result>D</result>
If x is real, find the maximum value of the expression -2x^2 + 11x + 13.