请问:无穷等比数列{an}的前n项和是S=a1/(1-q)还是Sn=a1(1-q^n)/(1-q)?
问题描述:
请问:无穷等比数列{an}的前n项和是S=a1/(1-q)还是Sn=a1(1-q^n)/(1-q)?
请问:无穷等比数列{an}的前n项和是S=a1/(1-q)还是Sn=a1(1-q^n)/(1-q)?
答
无穷等比数列{an}的前n项和是Sn=a1(1-q^n)/(1-q)?.当q〈1且n趋近于无穷大时(1-q^n)趋近于1,此时为 Sn=a1/(1-q).查看原帖>>