题目内容
计算:
(1)
+
-
;
(2)(
-
)•
.
(1)
| b |
| a-b |
| a |
| a+b |
| 2ab |
| b2-a2 |
(2)(
| 2x |
| x-3 |
| x |
| x+3 |
| x2-9 |
| x |
(1)原式=
+
+
=
=
;
(2)原式=
•
-
•
=2(x+3)-(x-3)=2x+6-x+3=x+9.
| ab+b2 |
| a2-b2 |
| a2-ab |
| a2-b2 |
| 2ab |
| a2-b2 |
| (a+b)2 |
| (a+b)(a-b) |
| a+b |
| a-b |
(2)原式=
| 2x |
| x-3 |
| (x+3)(x-3) |
| x |
| x |
| x+3 |
| (x+3)(x-3) |
| x |
=2(x+3)-(x-3)=2x+6-x+3=x+9.
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计算(
-
)×
的结果是( )
| a2+b2 |
| a2-b2 |
| a-b |
| a+b |
| a-b |
| 2ab |
A、
| ||
B、
| ||
| C、a-b | ||
| D、a+b |