3. Prove: the equation
has no integer solutions.
3. Prove: the equation
has no integer solutions.
Let be a set of integer solutions to equation (1). Clearly, , and
From this, we know that , hence and have the same sign.
Without loss of generality, assume and are both positive integers (otherwise, replace and with and respectively), and .
Consider equation (1) as a quadratic equation in
Thus, from a set of positive integer solutions of equation (1), we can derive another set of positive integer solutions
The above process can be carried out infinitely, each time yielding a new set of solutions where the sum of the two numbers is strictly less than the sum of the two numbers in the previous set, and all these solutions are positive integer solutions, which is clearly impossible. Therefore, the original indeterminate equation has no integer solutions.