# Factor completely 49x^{2} - 81.

(7x + 9)^{2}, (7x - 9)^{2}, (7x + 9)(7x - 9), 7x - 9

**Solution:**

Given: Expression is 49x^{2} - 81

In order to find roots, we need to factor the given polynomial.

⇒ 49x^{2} - 81

⇒ ((7x)^{2} - 9^{2})

This is in the form (a^{2 }- b^{2}), we know that the difference of squares is (a^{2} - b^{2}) = (a + b)(a - b)

We can write ((7x)^{2} - 9^{2}) as (7x + 9) and (7x - 9)

⇒ (7x - 9)(7x + 9) = 0

Therefore, the factors of 49x^{2} - 81 are(7x - 9)(7x + 9).

## Factor completely 49x^{2} - 81.

**Summary:**

Factors of 49x^{2} - 81 are(7x - 9)(7x + 9).