设一列数a1、a2、a3、···、a100中任意三个相邻数之和都是37,已知a2=25,a9=2x,a99=3-x,那么a100=?
人气:494 ℃ 时间:2020-03-24 11:41:49
解答
an+a(n+1)+a(n+2)=37
a(n+1))+a(n+2))+a(n+3)=37
所以an=a(n+3)
a100=a1
2x=a9=a99=3-x => x=1
a3=a9=2x=2
a1=37-a2-a3=10
a100=10
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