# Things get tricky here

**Algebra**Level pending

\(n\) and \(a\) are different real integers, where \(n≥0\) and \(a≥0\). Which of the following equations have the most real pair of integral solutions \((a,n)\) for any positive integer \(a\)?

1.\( \sqrt n - \sqrt{a-n} = a \).

- 2.\( \sqrt n - \sqrt{n-a} = a \)
- 3.\( \sqrt n + \sqrt{a-n} = a \)
4.\( \sqrt n + \sqrt{n-a} = a \)

Type your answer (1,2,3,or 4) and try not to use luck to finish this question lol.