(m+n)^2

The expression \((m+n)^2\) represents the square of the sum of \(m\) and \(n\). You can expand it using the formula for the square of a binomial:

\[ (m+n)^2 = m^2 + 2mn + n^2 \]

So, the expanded form of \((m+n)^2\) is \(m^2 + 2mn + n^2\).