Problem:
Do there exist prime numbers and such that ?
Problem:
Do there exist prime numbers and such that ?
Solution:
Write the given equation in the form
First observe that it must not be , since in this case the left hand side of (9) is greater than its right hand side. Hence, since and are distinct primes, (9) immediately yields , that is
for some . Since and are both primes, by (9) we get the following cases:
Case 1: , that is
for some . Substituting (11) into (10), and using the fact that and , we obtain
a contradiction.
Case 2: , that is
for some . Substituting (10) into (12), we get
If , then from (13) it follows that
or equivalently, , that is, . This implies that , and so . Hence, , but the pair and does not satisfy the equation (9).
Hence, it must be . Then if , (13) implies
or equivalently, , which is obviously impossible.
Thus, it must be and . For , (13) implies that , which by (12) again yields , which is impossible. Finally, for and , (13) gives , which is clearly not satisfied for any prime .
Hence, there do not exist prime numbers and which satisfy the given equation.