已知1=xy/x+y,2=yz/y+z,3=xz/x+z,求x+y+z的值
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人气：182 ℃ 时间：2019-12-05 02:44:49
解答
1=xy/(x+y)两边倒数1/x+1/y=1
同理 1/y+1/z=1/2
1/z+1/x=1/3
联合三个方程得1/x=5/12 1/y=7/12 1/z=-1/12
即x=12/5 y=12/7 z=-12
x+y+z=-276/35
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