Factor the expression 9x² - 81 by using the difference of two squares method.

To give your answer for this question, write the values for k, l, m and n, where k, l, m and n are constants in the factored expression (kx + m)(lx + n), and k has a greater absolute value than l (this doesn’t apply if both k and l are equal).

k =

l =

m =

n =