题目内容
用二次项定理证明32n+2-8n-9能被64整除(n∈N).
见解析
证明:32n+2-8n-9=9n+1-8n-9=(8+1)n+1-8n-9
=8n+1+8n+…+82+8+-8n-9
=64(8n-1+8n-2+…+)+8(n+1)+1-8n-9
=M×64(记M=8n-1+8n-2+…+).
∵M为整数,∴64M能被64整除.
=8n+1+8n+…+82+8+-8n-9
=64(8n-1+8n-2+…+)+8(n+1)+1-8n-9
=M×64(记M=8n-1+8n-2+…+).
∵M为整数,∴64M能被64整除.
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