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In pairs (Posted on 2019-07-09) Difficulty: 2 of 5
xy/(x+y)=3
yz/(y+z)=4
zx/(z+x)=5
xyz/(xy+yz+zx)=?

No Solution Yet Submitted by Danish Ahmed Khan    
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solution | Comment 1 of 3
Invert each equation to get an easily solved system expressed in reciprocals of x,y,z.

x=120/17
y=120/23
z=120/7

xyz/(xy+yz+zx)=1/(1/x+1/y+1/z)=120/47.

  Posted by xdog on 2019-07-09 17:39:39
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