Question

Find the derivative of f(x) = -12x^2 + 9x at x = 6.

Answer 1

-112.5

-135

-90

-108

Answer 2

f'=-24x+9

Answer 3

f(x) = -12x^2 + 9x
f(6) = -12(6)^2 + 9(6)
= -12 (36) + 54
= -432 + 54
= -378

Answer 4

^That's what I got but it's not an answer choice

Answer 5

but thats the correct one

Answer 6

I know

Answer 7

No that is the process of simply putting in 6 for 'x' you need first to find the derivative of the function...

\[\large f(x) = -12x^2 + 9x\]
\[\large f'(x) = -24x + 9\]

and you THEN substitute the value of 6 in for 'x'

Answer 8

oh ya then u'll get -135

Answer 9

thanks guys!!

Answer 10

anytime :)

Answer 11

welcome