D. 8. Which expression is a factor 16x^2-81 7 4x-9 Do 4x-81 Do 8x-9 Do 8x-81

To factor the expression $16x^{2}-81$, we can use the difference of squares formula, which states that $a^2 - b^2 = (a + b)(a - b)$.<br /><br />In this case, we have $16x^{2}-81$, which can be rewritten as $(4x)^{2} - 9^{2}$.<br /><br />Using the difference of squares formula, we can factor this expression as $(4x + 9)(4x - 9)$.<br /><br />Therefore, the correct answer4x-9$.