📝 题目
例 7 求 ${\left( \cos \left( x + b\right) \right) }^{\prime }$ 和 ${\left( \ln \left( x + c\right) \right) }^{\prime }$ .
💡 答案与解析
解 利用复合函数求导法则可得
$$ {\left( \cos \left( x + b\right) \right) }^{\prime } = \left( {-\sin \left( {x + b}\right) }\right) {\left( x + b\right) }^{\prime } $$
$$ = - \sin \left( {x + b}\right) , $$
$$ {\left( \ln \left( x + c\right) \right) }^{\prime } = \frac{1}{x + c}{\left( x + c\right) }^{\prime } = \frac{1}{x + c}. $$