If x is real, find the maximum value of the expression -2x^2 + 9x + 11. Pick:
A) 12.125
B) 15.125
C) 18.125
D) 21.125
E) 24.125
This is an equation of a downward facing parabola.   The maximum value is the top point of the parabola.   -2x^2+9x+11 = (-2x+11)(x+1)   The roots are 11/2 and -1.   The maximum value must be when x is halfway between these two points.   x = 2.25   The maximum value is -2(2.25)^2+9(2.25)+11 = 21.125   The answer is 21.125.
<result>D</result>
If x is real, find the maximum value of the expression -2x^2 + 9x + 11.