首页 > 留学知识库

问题: 计算下列极限

解答:

(x->0)lim(tanx-sinx)/x
=(x->0)lim(tanx-tanxcosx)/x
=(x->0)lim[(tanx/x)(1-cosx)]
=1*(1-1)
=1*0
=0
如果是(x->0)lim(tanx-sinx)/x^3
=(x->0)lim[tanx/x*(1-cosx)^2/x^2]
=(x->0){(tanx/x)*2[sin(x/2)]^2/x^2
=(x->0)lim(tanx/x*2(1/4)lim{[sin(x/2)]/(x/2)}^2
=1*(1/2)*1^2
=1/2