(m+n)²

The expression \((m+n)^2\) can be expanded using the binomial theorem or by applying the formula for the square of a sum. The expansion is:

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

So, the result of expanding \((m+n)^2\) is \(m^2 + 2mn + n^2\).