a |
b |
an |
bn |
a |
y |
x |
b |
n |
m |
2m |
n |
4 |
x |
2 |
x |
a |
b2 |
2a2 |
b2 |
A.①③ | B.①④ | C.②④ | D.③④ |
2x2y |
3mn2 |
5m2n |
4xy2 |
5xym |
3n |
a2 |
-b |
c2 |
-ab |
bc |
a |
2x |
3y |
3y |
4x |
a-b |
ab |
ab |
b-a |
2a |
b2 |
b2 |
4a4 |
a |
b |
b2 |
a |
a-1 |
a-b |
b2-a2 |
1-a |
A.a+b | B.-a+b | C.a-b | D.-a-b |
x2 |
3y |
9y3 |
x4 |
x2-1 |
x+1 |
x2-2x+1 |
x2-x |
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