(1)(-4x-3y2)(3y2-4x), =(-4x)2-(3y2)2, =16x2-9y4;
(2)(3a2+b)(3a2-b)(9a4-b2), =[(3a2)2-(b)2](9a4-b2), =(9a4-b2)2, =81a8-a4b2+b4;
(3)a(a-b)2-2b(a-b)(a+b), =a(a2-2ab+b2)-2b(a2-b2), =a3-2a2b+ab2-2a2b+2b3, =a3-4a2b+ab2+2b3;
(4)(a2-ab+b2)(a2+ab+b2), =[(a2+b2)2]-(ab)2, =a4+a2b2+b4. |