Question

Given f(2x+1) = x^2 +2x +1. find f'(x).

Answer 1

sorry. should be find f ' ( 2x +1 )

Answer 2

ah, that makes it a little easier
do you know the chain rule?

Answer 3

I know chain rule

Answer 4

ok, differentiate above using the chain rule on the left, and the power rule on the right. It won't be difficult to get f'(2x+1) after that.

Answer 5

keira what do you get on the left after differentiating?

Answer 6

I dont know. hehe

Answer 7

I've tried, but I dont know how to do it

Answer 8

The Chain rule is\[\frac{d}{dx}f(u)=f'(u)\frac{du}{dx}\]use\[u=2x+1\]and tell me what you get.

Answer 9

2 ?

Answer 10

well partly, but you have to keep the f'(u) part, that is important.

Answer 11

I dont know hw to do the f'(u) part. :(

Answer 12

just leave it as it is and sub in\[u=2x+1\]

Answer 13

so the answer is x + 1 ?

Answer 14

yes :)

Answer 15

thanks a lot ! :)