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问题: 求极限: lim (1 / x )^tgx

lim
x-0^+

解答:

y=(1/x)^tgx--->lny=-tgxlnx=lnx/(-ctgx)
x-->+0:limlny=lim[lnx/(-ctgx)]
=lim{(1/x)/[1/(sinx)^2)]}
=lim[(sinx)^2/x]
=limsinx*lim(sinx/x)
=0*1=0
--->limy==e^0=1