Question

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

Answer 1

Can you first find the derivative of -12x^2 + 9x?

Answer 2

I'm not sure how to do this type of problem

Answer 3

okay differential of sum is sum of differentials
d/dx(-12x^2)=-12 * d/dx(x^2)

Can you do that part?

Answer 4

is there an easier way to do this? i don't understand the d/dx

Answer 5

d/dx means differential with respect to x.

Answer 6

i still don't understand how to do it

Answer 7

Do you know the differential of x^n?

Answer 8

the notes i have did it in more of a step by step simpler way, but in my notes i only have an equation that begins with x^2, not necessarily with a coefficient in front of it

Answer 9

Okay the differential of x^n is nx^n-1

You could check it for x^2

d/dx(x^2)=(2)(x)^(2-1)=2x

Answer 10

i think i got it, is it -135? @AravindG

Answer 11

Wonderful! :) You are right

Answer 12

thanks a lot!