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2/1+4/1+8/1+31/1+62/1+124/1+248/1+496/1=?要用简便计算,
题目详情
2/1+4/1+8/1+31/1+62/1+124/1+248/1+496/1=?要用简便计算,
▼优质解答
答案和解析
整个式子再加上1/496再减去就求出来了
原式=1/2+1/4+.+1/248+1/496+1/496-1/496
=1/2+1/4+.+1/248+1/248-1/496
=...
=1/2+1/4+1/8+2/31
=7/8+2/31-1/496
=7/8+31/496
=7/8+1/16
=15/16
原式=1/2+1/4+.+1/248+1/496+1/496-1/496
=1/2+1/4+.+1/248+1/248-1/496
=...
=1/2+1/4+1/8+2/31
=7/8+2/31-1/496
=7/8+31/496
=7/8+1/16
=15/16
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