Question

已知数列an=3n,bn=2^(n-1),{anbn},{((-1)^(n+1)anbn}的偶数项和分别为Tn,Gn,是

Answer 1

Tn=(2+2n)/2*3+2(1-4^n)/(1-4)

Gn=-(2+2n)/2*3-2(1-4^n)/(1-4)

Tn+3Gn=-(2+2n)*3-4(4^n-1)/3=-14/3-6n-4^(n+1)/3

令-14/3-6n-4^(n+1)/3+15λ