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极限问题(急)第一题:lim的x趋近于无穷大(x-1)/(x+1)的x次方第二题:lim的x趋近于1 1/(x-1)减去

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极限问题(急)
第一题:lim的x趋近于无穷大(x-1)/(x+1)的x次方
第二题:lim的x趋近于1 1/(x-1)减去2/(x的平方-1)
(1)原式等于
lim[1-2/(x+1)]^{[-(x+1)/2]*[-2x/(x+1)]}
=lim{[1-2/(x+1)]^{[-(x+1)/2]}^[-2x/(x+1)]
=e^lim[-2x/(x+1)]
=e^{-2lim[x/(x+1)]}
=(1/e^2)^lim[1-1/(x+1)]
=1/e^2
(2)原式等于
lim[1/(x-1)-2/(x^2-1)]
=lim[(x+1)/(x^2-1)-2/(x^2-1)]
=lim{(x-1)/[(x+1)(x-1)]}
=lim1/(x+1)
=1/2