Find positive integers satisfying and .
Submit your answer as the value of .
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The equation is equivalent to 1 9 x y z = 9 7 ( y z − z − 1 ) or 1 9 x y z + 9 7 = 9 7 z × ( y − 1 ) .
1 9 and 9 7 are primes and so 9 7 should divide one of x , y , z . Also z should divide 9 7 which means that z = 9 7 is prime.
From this it follows that y divides 9 8 = 2 × 4 9 = 2 × 7 2 ; y being less than z = 9 7 . The possibilities are y = 2 , y = 7 , y = 1 4 , y = 4 9 .
If y = 2 , 1 9 × 2 × x = 2 × 9 7 − 9 8 = 9 6 so that x is not an integer.
If y = 7 , 1 9 x = 8 3 so that x is not an integer.
If y = 1 4 , 1 9 x = 9 0 so that x is not an integer.
If y = 4 9 , 1 9 × 4 9 x = 4 9 × 9 7 − 9 8 . i . e . , x = 5 .
Thus x = 5 , y = 4 9 , z = 9 7 .
Therefore x + y + z = 5 + 4 9 + 9 7 = 1 5 1 .