This is supposed to be proven:
limn→∞n−−√n=1
limn→∞nn=1
The sequence is monotone decreasing and has a lower bound of 11. So ϵ=0ϵ=0
With the Archimedean Property we get:
n0>1+2ϵ2
n0>1+2ϵ2
(What's that? 22? epsilon squared? Where does this come from?)
The binomic theorem yields:
n=(n−−√n)n=(1+(n−−√n−1))n=∑k=0n(nk)(n−−√n−1)k⩾(n2)(n−−√n−1)2=n(n−1)2(n−−√n−1)2
n=(nn)n=(1+(nn−1))n=∑k=0n(nk)(nn−1)k⩾(n2)(nn−1)2=n(n−1)2(nn−1)2
(how do I know that: (n−−√n)n=(1+(n−−√n−1))n(nn)n=(1+(nn−1))n ?, why is kk suddenly 22?)
Then:
(n−−√n−1)2⩽2n−1
(nn−1)2⩽2n−1
and
0