Question

求大神讲解一下谢谢了

等价无穷小怎么用啊 下面可以化为1/2x*2 上面怎么写呢？ 求讲解？

Answer 1

x->0

分母

cosx -1 = -(1/2)x^2+o(x^2)

分子

 (1+x^2+x^3)^(1/3)

= (1+x^2+o(x^2))^(1/3)

=1 + (1/3)x^2 +o(x^2)

(1+x^2+x^3)^(1/3) -1 =(1/3)x^2 +o(x^2)

lim(x->0) [ (1+x^2+x^3)^(1/3) -1] /(cosx -1)

=lim(x->0)(1/3)x^2 /[-(1/2)x^2]

=-2/3

ans :B