题目内容
若A=x2-2xy+y2,B=x2+2xy+y2,则4xy=( )
| A.B-A | B.B+A | C.A-B | D.2A-2B |
∵A=x2-2xy+y2,B=x2+2xy+y2,
∴B-A=(x2+2xy+y2)-(x2-2xy+y2)=x2+2xy+y2-x2+2xy-y2=4xy,
则4xy=B-A.
故选A
∴B-A=(x2+2xy+y2)-(x2-2xy+y2)=x2+2xy+y2-x2+2xy-y2=4xy,
则4xy=B-A.
故选A
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