1 (a-2b)2 2 (a-b)2 13 ( -2)2= -2x+ 4. (3x+2y)2-(3x-2y)2 5 (3a2-2a+1)(3a2+2a+1) 7. (a+3b)2 9 (a+3b)2-(3a+b) 11. (3y+2x)2 13. (3a+2b)2-(3a-2b)2 6. (a-b)2=a2-ab+b2 8. (x+9)(x-9)=x2-9 10. (5x2-4y2)(-5x2+4y2) 1212. -(-2x3n+2-3x2+n)2 14. (x2+x+6)(x2-x+6) 15. (a+b+c+d) 16. (9-a2)2-(3-a)(3-a)(9+a)2 . 2117. (x3+2)2-2(x+2)(x-2)(x2+4)-(x2-2)2,其中x=-2. 18. 20012 19. 9992 20.证明:(m-9)2-(m+5)2是28的倍数,其中m为整数.(提示:只要将原式化简后各项均能被28整除) 21.解方程:(x2-2)(-x2+2)=(2x-x2)(2x+x2)+4x 22. (x+2)(x-3)+(x+2)(x+4) 23. 2(a-3)(a-3)-a+3 24. (x + a)2 – (x – a)2 25. 1990×29-1991×71+1990×71-29×1991 26. (x2332y) 2 27. (m2n)2 28. (m1)(m1)(m21) 29. (xy)2(xy)2 30. (2xyz)(2xyz) 本文来源:https://www.wddqw.com/doc/315568ef4afe04a1b071de18.html