# How do you differentiate f(x)=sin(3x+1) using the chain rule?

I found: $3 \cos \left(3 x + 1\right)$
First you differentiate the $\sin$ as it is (in red) and then the argument (in blue) and multiply together:
$f ' \left(x\right) = \textcolor{red}{\cos \left(3 x + 1\right)} \cdot \textcolor{b l u e}{3} = 3 \cos \left(3 x + 1\right)$