题目内容
(1+
+
+…+
)×(
+
+
+…+
+
)-(1+
+
+…+
+
)×(
+
+
+…+
).
| 1 |
| 2 |
| 1 |
| 3 |
| 1 |
| 99 |
| 1 |
| 2 |
| 1 |
| 3 |
| 1 |
| 4 |
| 1 |
| 99 |
| 1 |
| 100 |
| 1 |
| 2 |
| 1 |
| 3 |
| 1 |
| 99 |
| 1 |
| 100 |
| 1 |
| 2 |
| 1 |
| 3 |
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| 4 |
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| 99 |
设
+
+
+…+
=a,
+
+
+…+
+
=b,
原式=(1+a)×b-(1+b)×a,
=b+ab-a-ab,
=b-a,
=
.
| 1 |
| 2 |
| 1 |
| 3 |
| 1 |
| 4 |
| 1 |
| 99 |
| 1 |
| 2 |
| 1 |
| 3 |
| 1 |
| 4 |
| 1 |
| 99 |
| 1 |
| 100 |
原式=(1+a)×b-(1+b)×a,
=b+ab-a-ab,
=b-a,
=
| 1 |
| 100 |
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