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

题目简介

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

题目详情

若A=x2-2xy+y2,B=x2+2xy+y2,则A-B=(  )
A.2x2+2y2B.2x2-2y2C.4xyD.-4xy
题型:单选题难度:中档来源:不详

答案

∵A=x2-2xy+y2,B=x2+2xy+y2,
∴A-B=(x2-2xy+y2)-(x2+2xy+y2)
=x2-2xy+y2-x2-2xy-y2
=-4xy,
故选D.

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