(1)(2m-3)(2m+5)(2)20052-2006×2004 (3)4(x+1)2-( 2x+5)(2x-5)(4)(a+b)(a-b)(a2+b2)(5
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(1)(2m-3)(2m+5) (2)20052-2006×2004 (3)4(x+1)2-( 2x+5)(2x-5) (4)(a+b)(a-b)(a2+b2) (5)(8xy2-6x2y+4xy)÷(-2x) (6)(a+b-c)(a+b+c) (7)20012 (8)(x+2y-3)2. |
答案
(1)(2m-3)(2m+5) =4m2+10m-6m-15 =4m2+4m-15;
(2)20052-2006×2004 =20052-(2005+1)×(2005-1) =20052-20052+1 =1;
(3)4(x+1)2-( 2x+5)(2x-5) =4(x2+2x+1)-(4x2-25) =4x2+8x+4-4x2+25 =8x+29;
(4)(a+b)(a-b)(a2+b2) =(a2-b2)(a2+b2) =a4-b4;
(5)(8xy2-6x2y+4xy)÷(-2x) =8xy2÷(-2x)-6x2y÷(-2x)+4xy÷(-2x) =-4y2+3xy-2y;
(6)(a+b-c)(a+b+c) =(aa+b)2-c2 =aa2+2aaba+b2-c2;
(7)20012 =(2000+1)2 =20002+2×2000×1+12 =4000000+4000+1 =4004001;
(8)(x+2y-3)2. =(x+2y)2-2(x+2y)×3+32 =x2+4xy+4y2-6x-12y+9. |
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