问题描述:
判别级数1/(5n-4)(4n+1)的敛散性,若收敛求其和
最佳答案:
1/(5n-4)(5n+1)=1/5·【1/(5n-4)-1/(5n+1)】Sn=1/5·【(1-1/6)+(1/6-1/11)+……+1/(5n-4)-1/(5n+1)】=1/5·【1-1/(5n+1)】∵limSn=1/5∴级数收敛,且其和为s=1/5
判别级数1/(5n-4)(4n+1)的敛散性,若收敛求其和,
问题描述:
判别级数1/(5n-4)(4n+1)的敛散性,若收敛求其和
1/(5n-4)(5n+1)=1/5·【1/(5n-4)-1/(5n+1)】Sn=1/5·【(1-1/6)+(1/6-1/11)+……+1/(5n-4)-1/(5n+1)】=1/5·【1-1/(5n+1)】∵limSn=1/5∴级数收敛,且其和为s=1/5