121x^2 - 81
The expression 121x^2 - 81 can be factored using a difference of squares formula.
The difference of squares formula states that a^2 - b^2 = (a + b)(a - b).
In this case, a is 11x and b is 9.
So, 121x^2 - 81 = (11x + 9)(11x - 9).
The difference of squares formula states that a^2 - b^2 = (a + b)(a - b).
In this case, a is 11x and b is 9.
So, 121x^2 - 81 = (11x + 9)(11x - 9).