(-5/^26)^2

To simplify the expression \((-5/^26)^2\), let's clarify the notation. If you mean \((-5/26)^2\), then we can simplify it as follows:

\[ (-5/26)^2 = (-5)^2 / (26)^2 = 25 / 676 \]

If you meant something different, please clarify your notation, and I would be happy to assist further!