你好!(arctan√x )' =1/(1+x) * (√x)'= 1/(1+x) * 1/(2√x)= 1/ [ 2(1+x)√x ][√arctanx] '= 1/ (2√arctanx) * (arctanx)'= 1/(2√arctanx) * 1/(1+x²)= 1/ [ 2(1+x²)√arctanx ]