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