abc = 64
a, b, c ∈ R^+
Find K that satisfy to the inequality :
(((a + b) (√(ab)) + (b + c) (√(bc)) + (c + a) (√(ca)))/(√(abc))) ≥ (√a) + (√b) + (√c) + K .
let f(x) =∫_0 ^(π/2) ln(1−xcost)dt with ∣x∣<1
1) developp f at integr serie
2) find a explicit form of f(x)
3) find the values of integrals ∫_0 ^(π/2) ln(1−cost)dt and ∫_0 ^(π/2) ln(1+cost)dt
4) calculate U_n =∫_0 ^(π/2) ln(1−(2/n)cost)dt with n integr and n≥2
study the convergence of U_n and Σ U_n