0879132人目の素数さん
2018/11/18(日) 02:10:29.27ID:ENzLbcND(1)
x = sinθ, y = sinφ (-π/2≦θ,φ≦π/2) とおく。
√(1-xx) = cosθ, √(1-yy) = cosφ,
x√(1-yy) + y√(1-xx) = sinθcosφ + sinφcosθ = sin(θ+φ),
両辺を2乗する。
(2)(左)
log{(m+n+1)!} -(m+n)log(m+n) > (3/2)log(m+n) -(m+n) +0.8918
log(m!) - m・log(m) < (1/2)log(m) -m +1,
log(n!) - n・log(n) < (1/2)log(n) -n +1,
辺々引くと
log{(m+n+1)!} -log(m!) -log(n!) -(m+n)log(m+n) +m・log(m) +n・log(n)
> (3/2)log(m+n) - (1/2)log(mn) - 1.1082
> (1/2)log(m+n) + (1/2)log{(m+n)^2 /4mn} + log(2) - 1.1082
≧ (1/2)log(m+n) - 0.41505
≧ (1/2)log(3) - 0.41505 (m+n≧3)
= 0.549306
(2)(右)
(m+n)^{m+n} = (m+n)^{m-n} (m+n)^{2n}
≧ m^{m-n} (4mn)^n
= m^m (4n)^n,
∴ (m+n)^(m+n)/(m^m・n^n) ≧ 4^n,
>>878
(3)
x/(1+x) は x≧0 で単調増加 (x∈R)
|a+b| ≦ |a| + |b|
∴ φ(|a+b|) ≦ φ(|a|+|b|)
= |a|/(1+|a|+|b|) + |b|/(1+|a|+|b|)
≦ φ(|a|) + φ(|b|),