First perform the multiplication (3*x* + 4)(3*x* - 4) since we know this is (9*x*^{2} - 16). Then we can multiply the two binomials (9*x*^{2} - 16) and (5*x* + 6). If instead we first multiplied (3*x* + 4) and (5*x* + 6), we would need to multiply (15*x*^{2} + 38*x* + 24) by (3*x* - 4), which would be an ugly calculation. Don't do that to yourself. You're a good person and deserve better. Whichever way we do it, though, we should find the same final answer of 45*x*^{3} + 54*x*^{2} - 80*x* - 96 |