RT,若（√2x-y）+y^2+4y+4=0,求[ - 知识问答

RT,若（√2x-y）+y^2+4y+4=0,求[(x-y)^2+(x+y)(x-y)]÷2x的值

3个回答

解
√2x-y+y²+4y+4=0
√2x-y+(y+2)²=0
∵√2x-y≥0,(y+2)²≥0
∴2x-y=0,y+2=0
∴y=-2,x=-1
∴[(x-y)²+(x+y)(x-y)]÷2x
=(x²-2xy+y²+x²-y²)÷2x
=(2x²-2xy)÷2x
=x-y
=-1+2
=1

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