First let's multiply the first and last term together: (3*x* + 4)(3*x* – 4) = 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: 45*x*^{3} + 54*x*^{2} – 80*x* – 96 |