计算1/2+1/6+1/12+1/20+1/30+1/42=_.
问题描述:
计算
+1 2
+1 6
+1 12
+1 20
+1 30
=______. 1 42
答
+1 2
+1 6
+1 12
+1 20
+1 30
=(1−1 42
)+(1 2
−1 2
)+(1 3
−1 3
)+(1 4
−1 4
)+(1 5
−1 5
)+(1 6
−1 6
),1 7
=1−
,1 7
=
.6 7
故应填
.6 7