Question

Find the derivative of f(x) = -12x2 + 9x at x = 6. a) -112.5 b)-135 c)90 d)108

Answer 1

hi

f(x) = -12x²+9x

So

f'(x) =  -24x +9

if  x = 6   then  f'(6) = -24 (6) +9 = -135