一、等差数列及其前
n项和等差数列的常用性质：
如果等差数列
{an}的首相时
<Object: word/embeddings/oleObject1.bin>
，公差为
d，那么
通项公式：
<Object: word/embeddings/oleObject2.bin>
=_____________________=___________________；
前n项和
<Object: word/embeddings/oleObject3.bin>
=__________________=_______________________；
<Object: word/embeddings/oleObject4.bin>
_______________；若
<Object: word/embeddings/oleObject5.bin>
,则________________________；
若{an}是等差数列，公差为
d，则{kan}也是等差数列，公差为
__________；
<Object: word/embeddings/oleObject6.bin>
也是等差数列，公差为__ ...