题目内容
计算:1+3
+5
+7
+9
+11
+13
+15
+17
+19
.
| 1 |
| 6 |
| 1 |
| 12 |
| 1 |
| 20 |
| 1 |
| 30 |
| 1 |
| 42 |
| 1 |
| 56 |
| 1 |
| 72 |
| 1 |
| 90 |
| 1 |
| 110 |
:1+3
+5
+7
+9
+11
+13
+15
+17
+19
,
=(1+19)+(3+17)+(5+15)+(7+13)+(9+11)+
+
+…+
+
,
=(1+19)+(3+17)+(5+15)+(7+13)+(9+11)+(
-
+
-
+…+
-
+
-
),
=20+20+20+20+20+(
-
),
=100
.
| 1 |
| 6 |
| 1 |
| 12 |
| 1 |
| 20 |
| 1 |
| 30 |
| 1 |
| 42 |
| 1 |
| 56 |
| 1 |
| 72 |
| 1 |
| 90 |
| 1 |
| 110 |
=(1+19)+(3+17)+(5+15)+(7+13)+(9+11)+
| 1 |
| 2×3 |
| 1 |
| 3×4 |
| 1 |
| 9×10 |
| 1 |
| 10×11 |
=(1+19)+(3+17)+(5+15)+(7+13)+(9+11)+(
| 1 |
| 2 |
| 1 |
| 3 |
| 1 |
| 3 |
| 1 |
| 4 |
| 1 |
| 9 |
| 1 |
| 10 |
| 1 |
| 10 |
| 1 |
| 11 |
=20+20+20+20+20+(
| 1 |
| 2 |
| 1 |
| 11 |
=100
| 9 |
| 22 |
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