cosx = 1 -(x^2)/2 +(x^4)/24-...e^(-x*x/2) = 1 -(x^2)/2 +(x^4)/8-...ln(1-x) = -x -(x^2)/2-(x^3)/3+...分子 = -(x^4)/12+...分母 = -(x^2)/2-(x^3)/3+...分子是更高阶的无穷小,这道题答案是0
