题目
题型：解答题难度：一般来源：不详
（2）5.6-7+3.4
（3）12×(
| 1 |
| 4 |
| 2 |
| 3 |
| 1 |
| 2 |
（4）-32×(-
| 1 |
| 3 |
| 1 |
| 2 |
答案
=1；
（2）原式=5.6+3.4-7
=9-7
=2；
（3）原式=12×
| 1 |
| 4 |
| 2 |
| 3 |
| 1 |
| 2 |
=3-8-6
=-11；
（4）原式=-9×（-
| 1 |
| 3 |
| 1 |
| 2 |
=3+32
=35．
核心考点
举一反三
（1）1-4+3-0.5
（2）-6×4+（-2.5）÷（-0.1）
| 1 |
| 1×2 |
| 1 |
| 2 |
| 1 |
| 2×3 |
| 1 |
| 2 |
| 1 |
| 3 |
| 1 |
| 3×4 |
| 1 |
| 3 |
| 1 |
| 4 |
| 1 |
| 4×5 |
| 1 |
| 4 |
| 1 |
| 5 |
（1）则第n个算式为______=______．
（2）如果将上列式子左右相加得：
| 1 |
| 1×2 |
| 1 |
| 2×3 |
| 1 |
| 3×4 |
| 1 |
| 4×5 |
| 1 |
| 2 |
| 1 |
| 2 |
| 1 |
| 3 |
| 1 |
| 3 |
| 1 |
| 4 |
| 1 |
| 5 |
| 1 |
| 5 |
| 4 |
| 5 |
| 1 |
| 1×2 |
| 1 |
| 2×3 |
| 1 |
| 3×4 |
| 1 |
| 2008×2009 |
②
| 1 |
| 1×2 |
| 1 |
| 2×3 |
| 1 |
| 3×4 |
| 1 |
| n×(n+1) |
（3）探究并计算
| 1 |
| 2 |
| 1 |
| 6 |
| 1 |
| 12 |
| 1 |
| 20 |
| 1 |
| 30 |
| 1 |
| 42 |
| 1 |
| 56 |
| 1 |
| 72 |
| 1 |
| 90 |