设Sn是等差数列An的前n项和,若S3⼀S6=1⼀3,则S6⼀S12等于

2025-06-28 03:37:23
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回答1:

Sn是等差数列
所以S3,S6-S3,S9-S6,S12-S9是等差数列
设S3=A.S6=3A,则S6-S3=2A,S9-S6=3A,S12-S9=4A
S9=6A,S12=10A
则S6/S12等于3/10