Câu 13 2.6: Cho chuỗi số sum _(n=1)^+infty sum _(n=1)^sum infty ((-1)^ncdot n^2)/(n^2)+1 Khi đó lim _(narrow infty )u_(n)=? a A B b C ) D 1.

The question asks for the limit of the general term of the series . Let . We want to find .As approaches infinity, the term approaches 1. Therefore, we have: The limit does not exist because the sequence oscillates between -1 and 1.Therefore, the limit of the general term does not exist.Final Answer: The final answer is