题目内容
计算或化简:
(1)
+20120+|-3|-4cos30°
(2)1-
÷
.
(1)
| 12 |
(2)1-
| a-1 |
| a |
| a2-1 |
| a2+2a |
(1)
+20120+|-3|-4cos30°
=2
+1+3-4×
=2
+4-2
=4;
(2)1-
÷
=1-
•
=1-
=
=-
.
| 12 |
=2
| 3 |
| ||
| 2 |
=2
| 3 |
| 3 |
=4;
(2)1-
| a-1 |
| a |
| a2-1 |
| a2+2a |
=1-
| a-1 |
| a |
| a(a+2) |
| (a+1)(a-1) |
=1-
| a+2 |
| a+1 |
=
| a+1-a-2 |
| a+1 |
=-
| 1 |
| a+1 |
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