if x is real , find the maximum value of the expression - 2 x ^ 2 + 11 x + 13 .
"this is an equation of a downward facing parabola . the maximum value is the top point of the parabola . - 2 x ^ 2 + 11 x + 13 = ( - 2 x + 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 d ."
subtract(add(multiply(11, divide(multiply(2, 2), 11)), 13), multiply(2, power(divide(multiply(2, 2), 11), 2)))