Determine the number of distinct positive triplets such that are distinct numbers that follows a geometric progression in that order.
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Since this is a geometric progression, we can write an equation based on the common ratio:
x + y + z x 2 + y 2 + z 2 = x 2 + y 2 + z 2 x 3 + y 3 + z 3 ( x 2 + y 2 + z 2 ) 2 = ( x + y + z ) ( x 3 + y 3 + z 3 ) x 4 + y 4 + z 4 + 2 x 2 y 2 + 2 x 2 z 2 + 2 y 2 z 2 = x 4 + y 4 + z 4 + x 3 y + x y 3 + x 3 z + x z 3 + y 3 z + y z 3 x 3 y − 2 x 2 y 2 + x y 3 + x 3 z − 2 x 2 z 2 + x z 3 + y 3 z − 2 y 2 z 2 + y z 3 = 0 x y ( x 2 − 2 x y + y 2 ) + x z ( x 2 − 2 x z + z 2 ) + y z ( y 2 − 2 y z + z 2 ) = 0 x y ( x − y ) 2 + x z ( x − z ) 2 + y z ( y − z ) 2 = 0
Note that since x = y = z , we know that x − y = 0 , x − z = 0 and y − z = 0
None of the numbers x , y and z are 0 . Suppose x = 0 . Then, y z ( y − z ) 2 = 0 , which implies that y = x = 0 or z = x = 0 , since y − z = 0 . This contradicts the fact that x = y = z . The same argument holds if y = 0 or z = 0
Then, suppose that x , y , z > 0 . We know that x y > 0 , ( x − y ) 2 > 0 , x z > 0 , ( x − z ) 2 > 0 , y z > 0 , ( y − z ) 2 > 0 . This implies that the expression x y ( x − y ) 2 + x z ( x − z ) 2 + y z ( y − z ) 2 > 0 .
Hence, 0 distinct positive triplets ( x , y , z ) satisfy the given requirements