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Diophantine Prime Pairs (Posted on 2024-08-08) Difficulty: 2 of 5
Find all pairs of prime numbers (p, q) for which 7pq2 + p = q3 + 43p3 + 1

No Solution Yet Submitted by Danish Ahmed Khan    
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Solution Analytic solution Comment 1 of 1
Parity check:
If p and q are both odd primes, then LHS is even and RHS is odd, so there are no solutions when both p and q are odd.

If q=2, 28p + p = 8 + 43p^3 + 1
43p^3 - 29p + 9 = 0 which has no integer solutions.

If p=2, 14q^2 + 2 = q^3 + 43*8 + 1
q^3 + 43*8 + 1 - 14q^2 - 2 = 0
q^3 - 14q^2 + 343 = 0
343 = 7^3
q=7 is a solution
q^3 - 14q^2 + 343 = (q-7)(q^2 - 7q - 49)
    the roots are q = {7, 7Φ, 7/Φ}
(p,q) = (2,7)  is the only solution

No programming required 
(but of course I did anyway, and only the one solution was found)


  Posted by Larry on 2024-08-08 09:41:50
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