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1/3*7+ 1/7/11+1/11*15+.+1/55*59
题目详情
1/3*7+ 1/7/11+1/11*15+.+1/55*59
▼优质解答
答案和解析
1/3*7+ 1/7*11+1/11*15+.+1/55*59
=1/4*(1/3-1/7)+1/4*(1/7-1/11)+1/4*(1/11-1/15)+.+1/4*(1/55-1/59)
=1/4*(1/3-1/7+1/7-1/11+1/11-1/15+.+1/55-1/59)
=1/4*(1/3-1/59)
=1/4*56/177
=14/177
=1/4*(1/3-1/7)+1/4*(1/7-1/11)+1/4*(1/11-1/15)+.+1/4*(1/55-1/59)
=1/4*(1/3-1/7+1/7-1/11+1/11-1/15+.+1/55-1/59)
=1/4*(1/3-1/59)
=1/4*56/177
=14/177
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