Factor completely.

25, x, squared, minus, 81
25x^2−81

1 answer

To factor the expression 25x^2 - 81 completely, we can rewrite it as a difference of squares:

25x^2 - 81 = (5x)^2 - 9^2

Now, we can factor the difference of squares:

(5x)^2 - 9^2 = (5x + 9)(5x - 9)

Therefore, the completely factored expression is (5x + 9)(5x - 9).