作业帮数列1/3.1/15.1/35.1/63······的前n项和sn
来源：学生作业帮助网 编辑：作业帮 时间：2024/11/15 12:17:21
x){6uӎz@D ڎg<{pI=y6IEd/!FBmmmm= ak $
5l
u!ꍁ4H)6GҠ f ĢiB̓rm @> r~
数列1/3.1/15.1/35.1/63······的前n项和sn
数列1/3.1/15.1/35.1/63······的前n项和sn
数列1/3.1/15.1/35.1/63······的前n项和sn
1/3+1/15+1/35+1/63+.+1/(2n-1)(2n+1)
=1/2*[1-1/3+1/3-1/5+1/5-1/7+.+1/(2n-1)-1/(2n+1)]
=1/2*[1-1/(2n+1)]
=n/(2n+1)