20/09/21 02:53:28.07 z8CeEVDW.net
>>686
P = (2m)!/{2^(2m)･(m!)^2}
= Π[k=1,m] (k - 1/2)/k
< Π[k=1,m] k/(k + 1/2)
< Π[k=1,m] k/√(k(k+1))
= Π[k=1,m] √{k/(k+1)}
= 1/√(m+1)
→ 0 (m→∞)
>>685 の方も相乗-相加平均を使い
(1-5/(6k))(1-4/(6k))(1-3/(6k))(1-2/(6k))(1-1/(6k))
< (1 - 3/(6k))^5
= ((k - 1/2)/k)^5
< (k/(k + 1/2))^5
< (k/√{k(k+1)})^{5/2}
= (k/(k+1))^{5/2},
P < Π[k=1,n] (k/(k+1))^{5/2}
= 1/(n+1)^{5/2}
→ 0 (n→∞)