计算:1-5/6+7/12-9/20+11/30-13/42+15/56-17/72=_.
问题描述:
计算:1-
+5 6
-7 12
+9 20
-11 30
+13 42
-15 56
=______. 17 72
答
1-
+5 6
-7 12
+9 20
-11 30
+13 42
-15 56
,17 72
=1-(
+1 2
)+(1 3
+1 3
)-(1 4
+1 4
)+(1 5
+1 5
)-(1 6
-1 6
)+(1 7
-1 7
)-(1 8
-1 8
),1 9
=1-
+1 2
,1 9
=
+1 2
,1 9
=
.11 18
故答案为:
.11 18