( x^2-b^2+y^2-a^2)^2-4(ab-xy)^2
问题描述：
( x^2-b^2+y^2-a^2)^2-4(ab-xy)^2
答
原式=(x²-b²+y²-a²+2ab-2xy)(x²-b²+y²-a²-2ab+2xy)=[(x-y)²-(a-b)²][(x+y)²-(a+b)²]=(x-y+a-b)(x-y-a+b)(x+y+a+b)(x+y-a-b)