Question 29. Theres 2 same-ratio sequences {a_n },{b_n } with a ratio of non-zero
And if two sums of each sequences (Σ_(n=1) ^∞ a_n ,Σ_(n=1) ^∞ b_n ) are convergent, and two equations
Σ_(n=1) ^∞ a_n b_n =(Σ_(n=1) ^∞ a_n )×(Σ_(n=1) ^∞ b_n ) and 3×Σ_(n=1) ^∞ ∣a_(2n) ∣=7×Σ_(n=1) ^∞ ∣a_(3n) ∣ are true.
If Σ_(n=1) ^∞ ((b_(2n−1) +b_(3n+1) )/b_n )=S, then Find the value of 120S.
(korea university exam question)
for every real set R , f∈R
and f is Smooth function. and f is f∈C^2
∀_x f^((1)) (x)>0 , f^((2)) (x)<0
then prove ∣∫_0 ^( t) cos(f(x))dx∣≤(2/(f^((1)) (t)))
t∈R