## Task Condition

Find the derivative.

$y=\ln ^{3}(1+\cos x)$
## Solution

$y^{\prime}=\left(\ln ^{3}(1+\cos x)\right)^{\prime}=3 \ln ^{2}(1+\cos x) \cdot \frac{1}{1+\cos x} \cdot(-\sin x)=-\frac{3 \cdot \sin x \cdot \ln ^{2}(1+\cos x)}{1+\cos x}$

## Problem Kuznetsov Differentiation 8-8