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

만약 A=x2-2xy+y2,B=x2+2xy+y2,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,그러므로 D 를 선택한다.