先从分子提出一个e，分母(√1+x²)³-1=(1+x²)^(3/2)-1等价无穷小为：(3/2)x²原式=lim[x→0] e(1-e^(cosx-1)) / [(3/2)x²]1-e^(cosx-1)等价于-(cosx-1)等价于(1/2)x²=lim[x→0] e(1/2)x² / [(3/2)x²]=3e
