y＝(sin2x)^2
y'
=2 sin2x (sin2x)'
=2 sin2x cos2x(2x)'
=4sin2xcos2x
=2sin4x=2 sin2x (sin2x)' 怎么来的呀复合函数求导法则[f(g(x))]'=f'(g(x))g'(x)没有学过么？