(1)(x2y-
xy2)2=x4y2-1 5
x3y3+2 5
x2y4;1 25
(2)原式=(a-b)2+4(a-b)+4=a2-2ab+b2+4a-4b+4;
(3)102×98=(100+2)(100-2)=1002-22=9996;
(4)10252-1023×1027,
=10252-(1025-2)(1025+2),
=10252-(10252-4),
=4;
(5)(m+1)2-5(m+1)(m-1)+3(m-1)2,
=m2+2m+1-5(m2-1)+3m2-6m+3,
=-m2-4m+9.