if x is real , find the maximum value of the expression - 2 x ^ 2 + 9 x + 11 .
"this is an equation of a downward facing parabola . the maximum value is the top point of the parabola . - 2 x ^ 2 + 9 x + 11 = ( - 2 x + 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 d ."
subtract(add(multiply(9, divide(multiply(2, 2), 9)), 11), multiply(2, power(divide(multiply(2, 2), 9), 2)))