- #1

hahaha158

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## Homework Statement

http://imgur.com/hCzGE

## Homework Equations

## The Attempt at a Solution

I was wondering, why I must take the chain rule of the top, but not the bottom?

should i not take chain rule for both (1-9x)^3 and (1-9x)^2, meaning the two derivatives of 9x (9) cancel out?

Thanks

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