下列计算正确的是( ) A.(a-b)2=a2-b2 B.(a-b)(b-a)=a2-b2 C.(a+b)(-a-b)=a2-b2 D.(-a-b)(-a+b)=a2-b2
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下列计算错误的是( ) A.(6a+1)(6a-1)=36a2-1 B.(-m-n)(m-n)=n2-m2 C.(a3-8)(-a3+8)=a9-64 D.(-a2+1)(-a2-1)=a4-1
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计算(-4x-5y)(5y-4x)的结果是( ) A.16x2-25y2 B.25y2-16x2 C.-16x2-25y2 D.16x2+25y2
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下列各式中,能用平方差公式计算的是( ) (1)(a-2b)(-a+2b); (2)(a-2b)(-a-2b); (3)(a-2b)(a+2b); (4)(a-2b)(2a+b). A.(1)(2) B.(2)(3) C.(3)(4) D.(1)(4)
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计算:51×49=_________.
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(1)(3a-4b)( )=9a2-16b2; (2)(4+2x)( )=16-4x2; (3)(-7-x)( )=49-x2; (4)(-a-3b)(-3b+a)=_______.
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下列计算对不对?若不对,请在横线上写出正确结果. (1)(x-3)(x+3)=x2-3( ),__________; (2)(2x-3)(2x+3)=2x2-9( ),_________; (3)(-x-3)(x-3)=x2-9( ),_________; (4)(2xy-1)(2xy+1)=2xy2-1( ),________.
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计算: (1)(a+1)(a-1)=_________;(3)(-a+1)(a+1)=________; (3)(-a+1)(a+1)=________;(4)(a+1)(-a-1)=_______.
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用字母表示平方差公式为:___________.
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已知:x=2a-b-c,y=2b-c-a,z=2c-a-b,试化简:(b-c)x+(c-a)y+(a-b)z.
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