- 设Sn是等差数列{An}的前n项和,若S3/S6=1/3,求S6?
- 设Sn是等差数列{An}的前n项和,若S3/S6=1/3,
求S6/S12?
请给出详细过程,谢谢
- S3=3(A1+A3)/2
S6=6(A1+A6)/2
S12=12(A1+A12)/2
S6-S3=2S3
(A1A2A3 A4A5A6 A7A8A9 A10A11A12)等差数列有规律的和也成等差数列)
S3 2S3 3S3 4S3
s6/s12=3s3/10s3=3/10我是有丰富经验的数学老师联系我数学将不再困难liangqingbo100@