问题
填空题
若{an}为等差数列,且
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答案
∵{an}为等差数列,且lim n→+∞
=2,an 2n+1
∴设an=4n+k,
∴公差d=an+1-an
=[4(n+1)+k]-(4n+k)
=4.
故答案为:4.
若{an}为等差数列,且
|
∵{an}为等差数列,且lim n→+∞
=2,an 2n+1
∴设an=4n+k,
∴公差d=an+1-an
=[4(n+1)+k]-(4n+k)
=4.
故答案为:4.