求极限,lim[xln(e+1/x)-x],x趋向于无穷大
问题描述:
求极限,lim[xln(e+1/x)-x],x趋向于无穷大
答
lim[x→∞][xln(e+1/x)-x]
=lim[x→∞]xln[1+1/(ex)]
=lim[x→∞]ln{[1+1/(ex)]^(ex)}^(1/e)
=1/e
答
令x=1/u,则u→0
原极限=lim[u→0] [(1/u)ln(e+u)-1/u]
=lim[u→0] [ln(e+u)-1]/u
洛必达法则
=lim[u→0] 1/(e+u)
=1/e