等差数列An满足a2=2,a5=8
3个回答
因为a2=2,a5=8,设公差为d
所以a5-a2=3d=8-2=6
所以公差d=2
首项a1=a2-d=2-2=0
所以通向公式等于
an=a1+(n-1)*d
=0+2(n-1)
=2n-2
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