A.9 | B.-9 | C.±9 | D.±18 |
A.①③ | B.②④ | C.③④ | D.①⑤ |
A.(a-b)2=a2-b2 | B.a2+b2=(a+b)2 |
C.(a-b)2=a2-2ab+b2 | D.(a+b)2=(a-b)2+2ab |
x |
2 |
y |
2 |
A.
| B.(
| C.
| D.
|
A.(x+2)2=x2+2x+4 | B.(-3-x)(3+x)=9-x2 |
C.(-3-x)(3+x)=-x2-9+6x | D.(2x-3y)2=4x2+9y2-12xy |
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