-a |
m-n |
A.
| B.
| C.
| D.-
|
-a |
m-n |
a |
m-n |
a |
-(m-n) |
a |
-m+n |
1 |
x-3 |
x+2 |
x2-x-6 |
A.x+2>0 | B.x+2=0 | C.x+2<0 | D.x+2≠0 |
2xy |
x-y |
A.变为原来的2倍 | B.不变 |
C.变为原来的4倍 | D.无法确定 |
5(3a+1) |
7(3a+1) |
5 |
7 |
-(a-b) |
c |
a-b |
c |
-x+y |
-x |
x-y |
x |
-a+b |
c |
a-b |
c |
-m-n |
m |
m-n |
m |
A..(1)(2) | B..(3)(4) | C..(1)(3) | D.(2)(4) |
x+y |
x-y |
A.扩大2倍 | B.扩大4倍 | C.缩小一半 | D.不变 |
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