题目内容：

y＝ [ f(x+tanx) ] ∧2求导

优质解答

y'=2f(x+tanx) [f(x+tanx)]'
=2f(x+tanx)f'(x+tanx) (x+tanx)'
=2f(x+tanx)f'(x+tanx)[1+(secx)^2]