if x is real , find the maximum value of the expression - 2 x ^ 2 + 5 x + 7 .
this is an equation of a downward facing parabola . the maximum value is the top point of the parabola . - 2 x ^ 2 + 5 x + 7 = ( - 2 x + 7 ) ( x + 1 ) the roots are 7 / 2 and - 1 . the maximum value must be when x is halfway between these two points . x = 1.25 the maximum value is - 2 ( 1.25 ) ^ 2 + 5 ( 1.25 ) + 7 = 10.125 the answer is c .
subtract(add(multiply(5, divide(multiply(2, 2), 5)), 7), multiply(2, power(divide(multiply(2, 2), 5), 2)))