1/30+1/42+1/56+1/72+1/90+1/110=?

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1/30+1/42+1/56+1/72+1/90+1/110=?
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1/30+1/42+1/56+1/72+1/90+1/110=?
1/30+1/42+1/56+1/72+1/90+1/110=?

1/30+1/42+1/56+1/72+1/90+1/110=?
1/2*15+1/2*21+1/2*28+1/2*36+1/2*45+1/2*55
=1/2*(1/15+1/21+1/28+1/36+1/45+1/55)
=1/2*(1/3*5+1/3*7+1/4*7+1/4*9+1/5*11)
=1/2*[1/3(1/5+1/7)+1/4(1/7+1/9)+1/55]
=1/2*[1/3(12/35)+1/4(16/63)+1/55]
=1/2*(4/35+4/63+1/55)
=1/2*[(4*63)/35*63+(4*35)/35*63+1/55]
=1/2*(252/2205+140/2205+1/55)
=1/2*(392/2205+1/55)
=1/2*[(392*11)/2205*11+441/55*441]
=1/2*(4312/24255+441/24255)
=1/2*(4753/24255)
=4753/48510
这是笨办法,有好办法的朋友发一下

1/30+1/42+1/56+1/72+1/90 1/30+1/42+1/56+1/72+1/90 1/30+1/42+1/56+1/72 简算 1/30+1/42+1/56+1/72简便算法 1/30+1/42+1/56+1/72＝ 简算1/30+1/42+1/56+1/72＝? 1/30+1/42+1/56+1/72= 30分之1+42分之一+56分之1+72分之一 1/2+1/6+1/12+1/20+1/30+1/42+1/56+1/72 1/2+1/6+1/12+1/20+1/30+1/42+1/56+1/72 1/12+1/20+1/30+1/42+1/56+1/72+1/90 1/12+1/20+1/30+1/42+1/56+1/72+1/90 1/6+1/12+1/20+1/30+1/42+1/56+1/72 简便计算 1/2+1/6+1/20+1/30+1/42+1/56+1/72等于多少? 1/2+1/6+1/20+1/30+1/42+1/56+1/72等于几? 1/6+1/12+1/20+1/30+1/42+1/56+1/72 1/12+1/20+1/30+1/42+1/56+1/72+1/90=? 1/6+1/12+1/20+1/30+1/42+1/56+1/72=?