摘要：观察下列各式: (x2-1) ÷(x-1)= x+1 (x3-1) ÷(x-1)= x2 +x+1 (x4-1) ÷(x-1)= x3+x2 +x+1 (x5-1) ÷(x-1)= x4+ x3+x2 +x+1 ---- 观察上面的规律计算: 1+2+ 22+--+ 262 +263= .

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