Final answer:
The equation x * x = a has at most two solutions in Z.
Step-by-step explanation:
In order to prove or disprove the statement, we need to consider different cases. Let's assume that for any n and a in Z, the equation x * x = a has more than two solutions in Z.
If a is 0, then x * x = 0 implies that x = 0. But this is only one solution, contradicting our assumption.
If a is a perfect square, then let's say a = m^2, where m is an integer. In this case, x * x = m^2 implies that either x = m or x = -m. These are only two solutions, again contradicting our assumption.
Therefore, we have shown that for any n and a in Z, the equation x * x = a has at most two solutions in Z.