y=lntanx/3求导

题目

y=lntanx/3求导

答案

y'=1/tan(x/3) ×[tan(x/3)]'
=1/tan(x/3)× [sec(x/3)]平方×(x/3)'
=1/[3sin(x/3)cos(x/3)]
=2/3sin(2x/3)