a1.a2.a3.a100中任意三个相临之和都是37,已知a2=25,a9=2x,a99=3-x,那么a100=____________
人气：220 ℃ 时间：2020-03-29 04:48:44
解答
即a1+a2+a3=37
a2+a3+a4=37
相减
a1-a4=0
a1=a4
同理a1=a4=a7=a10=……=a100
同样
a3=a6=a9=……=a99
所以2x=3-x
x=1
即a3=a9=2x=2
a1+a2+a3=37
a1=37-25-2=10
所以a100=a1=10
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