A=x2-2xy+y2,B=x2+2xy+y2,ならA-B=() A.2x2+2y2B.2x2-2y2C.4xyD.-4xy

A=x2-2xy+y2,B=x2+2xy+y2,ならA-B=() A.2x2+2y2B.2x2-2y2C.4xyD.-4xy

A=x2-2xy+y2、B=x2+2xy+y2、A-B=(x2-2xy+y2)-(x2+2xy+y2)=x2-2xy+y2-x2-2xy-y2=-4xy、故選D.