5÷(1×6)+5÷(6×11)+5÷(11×16)+5÷(16×21)
=5*[1/6+1/(6*11)+1/(11*16)+1/(16*21)]
=5*5*[1-1/6+1/6-1/11+1/11-1/16+1/16-1/21]
=25*[1-1/21]
=25*20/21
=500/21
=5*[1/6+1/(6*11)+1/(11*16)+1/(16*21)]
=5*5*[1-1/6+1/6-1/11+1/11-1/16+1/16-1/21]
=25*[1-1/21]
=25*20/21
=500/21
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第1个回答 推荐于2021-02-03
=5×1/6+5/11×1/6+5/11×1/16+5/16×1/21
=1/6×（5+5/11）+5/11×1/16+5/16×1/21
=1/6×60/11+5/11×1/16+5/16×1/21
=10/11+5/11×1/16+5/16×1/21
=2×5/11+5/11×1/16+5/16×1/21
=5/11×（2+1/16）+5/16×1/21
=5/11×33/16+5/16×1/21
=3×5/16+5/16×1/21
=5/16×（3+1/21）
=5/16×64/21
=20/21本回答被网友采纳
=1/6×（5+5/11）+5/11×1/16+5/16×1/21
=1/6×60/11+5/11×1/16+5/16×1/21
=10/11+5/11×1/16+5/16×1/21
=2×5/11+5/11×1/16+5/16×1/21
=5/11×（2+1/16）+5/16×1/21
=5/11×33/16+5/16×1/21
=3×5/16+5/16×1/21
=5/16×（3+1/21）
=5/16×64/21
=20/21本回答被网友采纳
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