wuyan： 莫非是平方? [阅读: 393] 2007-07-16 05:15:09 x + y + z = 6 1/x + 1/y + 1/z = 0 => 左右同乘xyz, xy+yz+xz=0 x2 + y2 + z2 (x+y+z)2 = x2 + y2 + z2 + 2xy + 2yz + 2xz = 36 xy + yz +xz = 0 所以是36
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