令x^x=y,对两边求对数,xINx=INy,再对两边求指数,e(xINx)=x^x=e(INy)
所以就有lim x^x=lim e^lny=e^lim lny;
=e^lim lnx^x =e^lim xlnx = e^lim (lnx )/(1/x)= ----(无穷除以无穷,采用罗比达法则上下求导)
=e^lim (1/x)/(-1/x^2) =e^lim(-x) =1
令x^x=y,对两边求对数,xINx=INy,再对两边求指数,e(xINx)=x^x=e(INy)
所以就有lim x^x=lim e^lny=e^lim lny;
=e^lim lnx^x =e^lim xlnx = e^lim (lnx )/(1/x)= ----(无穷除以无穷,采用罗比达法则上下求导)
=e^lim (1/x)/(-1/x^2) =e^lim(-x) =1