lin(x-1/x+1)^2x
问题描述:
lin(x-1/x+1)^2x
答
题目有点问题,下次注意给出x的趋向值,以及适当地加上括号
我猜这题是x趋于无穷:
lim(x→∞) [(x-1)/(x+1)]^(2x)
=lim [(x+1-2)/(x+1)]^(2x)
=lim [1 + (-2)/(x+1)]^(2x)
=lim [1 + 1/[(x+1)/(-2)] ^ (2x)
=lim [1 + 1/[(x+1)/(-2)] ^ 2*(x+1-1)*(-2)/(-2)
=lim [1 + 1/[(x+1)/(-2)] ^ [(-4)*(x+1)/(-2) + (-2)]
=lim {[1 + 1/[(x+1)/(-2)]^[(x+1)/(-2)]}^(-4) * lim [1 + 1/[(x+1)/(-2)]^(-2)
根据重要的极限:lim (1+1/x)^x=e
=e^(-4)*1
=e^(-4)
有不懂欢迎追问