(1)原式=-27a9b6•(-a6b9)=8a15b15; (2)原式=4(x-y)4•(y-x)3=4(y-x)7; (3)原式=-a5b3-a4b4-a3b3-2a4b4=-a5b3-3a4b4-a3b3; (4)原式=2x2+4x-16; (5)原式=6x2-xy-12y2; (6)原式=(x2-1)(x2+1)=x4-1; (7)原式=8x2-72; (8)原式=(-2a+3b+3a+2b)(-2a+3b-3a-2b)=(a+5b)(-5a+b)=-5a2+5b2-24ab; (9)原式=9962-(996-1)×(996+1)=9962-(9962-1)=1. |