输血狗299、315、322的问题，盼解答

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答案没错
x^1/2-y^1/2+z^1/2=0 把z移到右边然后square both sides
x+y-2(xy)^1/2 = z  
x+y-z=2(xy)^1/2   继续square both sides
x^2+y^2+z^2+2(xy-yz-xz)=4xy  
x^2+y^2+z^2=4xy-2(xy-yz-xz) =2(xy+yz+xz)