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下列运算正确的是( ) A.3x2-2x2=x2 B.(-2a)2=-2a2 C...
下列运算正确的是( )
A.3x2-2x2=x2
B.(-2a)2=-2a2
C.(a+b)2=a2+b2
D.-2(a-1)=-2a-1
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