Let x , y , z be distinct real numbers satisfying x + y 1 = y + z 1 = z + x 1 . Find the value of x 2 y 2 z 2 .
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This is incomplete. You still need to show that there exists distinct real numbers x , y , z that satisfy the constraints.
The word you have used distinct is not suitible here because on solving I have found that the solution exists if and only if x = y = z
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Agreed that for this problem to be well phrased, we need solution sets to the original expression.
As it turns out, there are non-disinct solutions. E.g. x = − 1 , y = 1 / 2 , 2 .
More generally, in addition to that solution and x = y = z = 1 , the solution sets are of the form ( x , − x + 1 1 , x x + 1 ) , ( x , 1 − x 1 , x x − 1 ) for x = 0 , 1 , − 1 . Do you see how to arrive at this conclusion? (Assuming that I haven't made a mistake, which could be possible).
@Kushal Bose Even I am also facing the same. But that's NMTC 2016 problem!
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G i v e n , x + y 1 = y + z 1 = z + x 1
→ x − y = z 1 − y 1 = y z y − z ( 1 )
→ y − z = x 1 − z 1 = x z z − x ( 2 )
→ z − x = y 1 − x 1 = x y x − y ( 3 )
M u l t i p l y i n g ( 1 ) , ( 2 ) a n d ( 3 ) , w e g e t
⇒ ( x − y ) ( y − z ) ( z − x ) = ( x y z ) 2 ( x − y ) ( y − z ) ( z − x )
∴ x 2 y 2 z 2 = 1