Suppose that there are non-negative integers y and z such that 1 +
45y = z2. If y = 0, then z2 = 2 which is impossible. Then y ≥ 1. Then
z2 = 1 + 45y ≥ 1 + 451 = 46. Thus, z ≥ 7. Now, we consider on the equation
z2 − 45y = 1. By Proposition 2.1, we have y = 1. Thus, z2 = 46. This is
a contradiction. Hence, the Diophantine equation 1 + 45y = z2 has no non-
negative integer solution.