已知当x→0时,x-sinx与ax^3是等价无穷小,求a
问题描述：
已知当x→0时,x-sinx与ax^3是等价无穷小,求a
答
lim(x→0) (x-sinx)/(ax^3)
=lim(x→0) (1-cosx)/(3ax^2)
=lim(x→0) (x^2/2)/(3ax^2)
=1/(6a)
=1
a=1/6