第1个回答 2010-12-11
(x^2+y^2)^2-4(x^2)(y^2)=(x^2+y^2)^2-(2xy)^2=(x^2+y^2+2xy)(x^2+y^2-2xy)=(x+y)^2(x-y)^2=(x^2-y^2)^2
1001^2-202202+101^2=1001^2-101*1001*2+101^2=(1001-101)^2=900^2=810000
99^2+198+1=99^2+2*98*1+1^2=(99+1)^2=100^2=10000
66^2+65^2-130*66=66^2-2*66*65-65^2=(66-65)^2=1^2=1