limx趋向无穷 xcos1/x的极限 limx趋向0xtanx的极限

题目

limx趋向无穷 xcos1/x的极限 limx趋向0xtanx的极限

答案

lim(x-->∞)cos1/x=1
lim(x-->∞)x=∞
∴x-->∞时,xcos1/x-->∞
lim(x-->∞)xcos1/x=∞
lim(x-->0)tanx=0
lim(x-->0)xtanx=0