# Thread: Prove a simple reduction formula (I get it almost right)

1. ## Prove a simple reduction formula (I get it almost right)

My answer would be correct if I didn't have that extra x variable. Why do I have it and how do I get rid of it?

Any input would be greatly appreciated!
Your $du$ is wrong. It should be : $du = n \left( ln(x) \right) ^{n-1} {\color{red} \frac{1}{x}} dx$.
If $n \in R$ and $y=\left( f(x) \right)^n$ , then:
$y' = n \left( f(x) \right)^{n-1} {\color{red} f'(x)}$.