题目内容
设一列数
中任意三个相邻数之和都是37,已知
那么
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10
解:由任意三个相邻数之和都是37可知:
a1+a2+a3=37
a2+a3+a4=37
a3+a4+a5=37
…
an+an+1+an+2=37
可以推出:a1=a4=a7=…=
a2=a5=a8=…=a3n+2
a3=a6=a9=…=a3n
∴a9=a99
即:a9=a99
2x=3-x
x=1
∴a3=2
∴
=37-25-2=10.
a1+a2+a3=37
a2+a3+a4=37
a3+a4+a5=37
…
an+an+1+an+2=37
可以推出:a1=a4=a7=…=
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a2=a5=a8=…=a3n+2
a3=a6=a9=…=a3n
∴a9=a99
即:a9=a99
2x=3-x
x=1
∴a3=2
∴
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