设：y = y1/y2 = e^x/x^3lim(x->∞) y = lim(x->∞) e^x/x^3 //: 用3次洛必达法则= lim(x->∞) e^x/3x^2= lim(x->∞) e^x/6x= lim(x->∞) e^x/6= ∞可见当 x->∞ 时，y1 >> y2 .
