当x->0时, cosx=1-x^2/2+x^4/24+o(x^4) e^{-x^2/2)=1-x^2/2+x^4/8+o(x^4) ln(1-x)=-x-x^2/2+o(x^2) 故分子=(1-x^2/2+x^4/24+o(x^4))-(1-x^2/2+x^4/8+o(x^4))=x^4/6+o(x^4)~x^4/6 分母=x^2[x+(-x-x^2/2+o(x^2))]=x^2(-x^2+o(x^2))~-x^4 原式=lim{x->0}[x^4/6]/(-x^4)=-1/6