求(sin^3x)/(tan(x^3))x趋于0时的极限如题

求(sin^3x)/(tan(x^3))x趋于0时的极限
如题

lim(x→0)sin^3x/tanx^3
用等价无穷小代换
=lim(x→0)3x/x^3
用洛必达法则
=lim(x→0)3/3x^2
=无穷