All about flooble | fun stuff | Get a free chatterbox | Free JavaScript | Avatars    
perplexus dot info

Home > Numbers
Some Prime Squares Sum Cube (Posted on 2023-05-21) Difficulty: 3 of 5
Find all triplet(s) (p, q, r) of prime numbers, that satisfy this equation:
          p3 = p2 + q2 + r2
Justify your answer with valid reasoning.

See The Solution Submitted by K Sengupta    
Rating: 4.5000 (2 votes)

Comments: ( Back to comment list | You must be logged in to post comments.)
solution | Comment 2 of 4 |
p^3 - p^2 is divisible by 3 for any integer >0.

The possible cases are q=r=2, or q=r=3, or one of q,r=2 with the other odd, or both of q,r=odd.  

Only the second case allows a solution:  (p,q,r)=(3,3,3). 

**edit**
Careless and incorrect since if p=2 mod 3, p^3 - p^2 is not divisible by 3.  Ignore. 

Edited on May 21, 2023, 1:18 pm
  Posted by xdog on 2023-05-21 12:22:52

Please log in:
Login:
Password:
Remember me:
Sign up! | Forgot password


Search:
Search body:
Forums (0)
Newest Problems
Random Problem
FAQ | About This Site
Site Statistics
New Comments (3)
Unsolved Problems
Top Rated Problems
This month's top
Most Commented On

Chatterbox:
Copyright © 2002 - 2024 by Animus Pactum Consulting. All rights reserved. Privacy Information