Factor.
\[
81 w^{2}-4 v^{2}
\]
The factored form of the expression \(81 w^{2}-4 v^{2}\) is \(\boxed{(-2v + 9w)(2v + 9w)}\).
Step 1 :This is a difference of squares problem. The difference of squares formula is a^2 - b^2 = (a - b)(a + b).
Step 2 :In this case, a = sqrt(81w^2) = 9w and b = sqrt(4v^2) = 2v.
Step 3 :So we can apply the formula to factor the expression.
Step 4 :The factored form of the expression \(81 w^{2}-4 v^{2}\) is \(\boxed{(-2v + 9w)(2v + 9w)}\).