lim(x趋向于无穷大)(1-2/x)^(x/2-1)极限详解

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lim(x趋向于无穷大)(1-2/x)^(x/2-1)极限详解

lim(x趋向于无穷大)(1-2/x)^(x/2-1)极限详解
lim(x趋向于无穷大)(1-2/x)^(x/2-1)极限详解

lim(x趋向于无穷大)(1-2/x)^(x/2-1)极限详解
首先你应该知道(1+1/n)^n=e (e的定义之一)
lim(x->inf)(1-2/x)^(x/2-1) = lim(x->inf)(1-2/x)^(x/2) * lim(x->inf)(1-2/x)^(-1)
其中lim(x->inf)(1-2/x)^(-1) 等于1
所以 lim(x->inf)(1-2/x)^(x/2-1) = lim(x->inf)(1-2/x)^(x/2)
令 x/2=t (t趋向于无穷大)
lim(t->inf)(1-1/t)^t = [ (1-1/t)(1+1/t)/(1+1/t)]^t
= [(1-1/t^2)/(1+1/t)]^t
= [1/(1+1/t)]^t - [1/t^2)/(1+1/t)]^t
=1^t/ (1+1/t)^t -1/(t^2+t) 前半带公式 后半极限为0
=1/e