Need guidance on this one.

Find the local maximum and minimum values of the function f (ac) = - a - 81 using the Second Derivative Test. Complete all steps of the adaptive question below. Note: you will be required to explain your reasoning at the end of the adaptive sections. Enter the points in increasing order of their -coordinates. Click "Continue" to begin. Enter the first point in the form (x, y): (9, -18) the sign of f (x ) is negative Section Attempt 2 of 3