f(x)=sin^3(3x+1)
设sin(3x+1)=u,3x+1=v
则：
f'(x)=[y'|u]*[u'|v]*[v'|x]
=[(u^3)']*[(sinv)']*[(3x+1)']
=[3u^2]*[cosv]*[3]
=[3sin^2(3x+1)]*[cos(3x+1)]*3
=9sin^2(3x+1)cos(3x+1)