## College Algebra (11th Edition)

($y^{2}$ + 9)($y^{2}$ - 9)
We know that (a + b)(a - b) = $a^{2}$ - $b^{2}$, so we take the square root of each term in the polynomial to get a and b. We get $y^{2}$ and 9, so the factorization is ($y^{2}$ + 9)($y^{2}$ - 9).