Prove that the equation has no solution in the set of the positive integers.
Solutions — 2
Solution 1
We assume the contrary is true. So there are and that satisfy the equation. Hence we have
But , so will have at least one prime divisor of the type . It is known (and easily obtainable by using Fermat's Little Theorem) that this is impossible.
Solution 2
1. Start with the given equation:
2. Rearrange the equation to isolate :
3. Factor the right-hand side:
4. Consider the expression . Notice that:
This is because and .
5. Since , there exists a prime such that .
6. Now, consider the prime and the expression . If , then .
7. However, for a prime , is not a quadratic residue modulo . This means that there is no integer such that .
8. Therefore, implies that , which is impossible because is not a quadratic residue modulo .
9. Hence, there is no solution in the set of positive integers for the given equation.