题目内容
若{an}是公差为1的等差数列,则{a2n-1+2a2n}是( )
A.公差为3的等差数列 | B.公差为4的等差数列 |
C.公差为6的等差数列 | D.公差为9的等差数列 |
设{an}的公差为d,则d=1,
设cn=a2n-1+2a2n,则cn+1=a2n+1+2a2n+2,
∴cn+1-cn=a2n+1+2a2n+2-a2n-1-2a2n=6d=6,
故选C.
设cn=a2n-1+2a2n,则cn+1=a2n+1+2a2n+2,
∴cn+1-cn=a2n+1+2a2n+2-a2n-1-2a2n=6d=6,
故选C.
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