来自蔡志远的问题
lim(x->0)(1/(tanx)^2-1/(x)^2
lim(x->0)(1/(tanx)^2-1/(x)^2
1回答
2020-12-21 06:42
lim(x->0)(1/(tanx)^2-1/(x)^2
lim(x->0)(1/(tanx)^2-1/(x)^2
lim(x->0)1/(tanx)^2-1/(x)^2
=lim(x->0)[1/(sinx)^2-1]-1/(x)^2
=-1+lim(x->0)[x^2-(sinx)^2]/x^2(sinx)^2
=-1+lim(x->0)[x^2-(sinx)^2]/x^4
=-1+lim(x->0)[x-sinxcosx]/2x^3
=-1+lim(x->0)[1-(cosx)^2+(sinx)^2]/6x^2
=-1+lim(x->0)[2(sinx)^2]/6x^2
=-2/3