19/20+29/30+41/42+55/56+71/72= 简便方法做

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19/20+29/30+41/42+55/56+71/72=简便方法做19/20+29/30+41/42+55/56+71/72=简便方法做19/20+29/30+41/42+55/56+71/72=

19/20+29/30+41/42+55/56+71/72= 简便方法做
19/20+29/30+41/42+55/56+71/72= 简便方法做

19/20+29/30+41/42+55/56+71/72= 简便方法做
19/20+29/30+41/42+55/56+71/72
=1-1/20+1-1/30+1-1/42+1-1/56+1-1/72
=5-(1/20+1/30+1/42+1/56+1/72)
=5-(1/4-1/5+1/5-1/6+1/6-1/7+1/7-1/8+1/8-1/9)
=5-(1/4-1/9)
=5-5/36
=4又29/36