How should I start expanding two quadratics? Do I factor and then do it the long way?

(x^2-6x+9)(x^2+8x+13)

How should I start expanding two quadratics? Do I factor and then do it the long way?

(x^2-6x+9)(x^2+8x+13)

(x^2-6x+9)(x^2+8x+13)

- stapel_eliz
**Posts:**1628**Joined:**Mon Dec 08, 2008 4:22 pm-
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Factoring is going in the wrong direction. You're not wanting to take this apart; you're wanting to multiply it all together.How should I start expanding two quadratics? Do I factor and then do it the long way?

Once you have this many terms,(x^2-6x+9)(x^2+8x+13)

So, just like you use vertical multiplication for multiplying three-digit and larger numbers, use a vertical set-up here:

start like this: x^2 - 6x + 9 x^2 + 8x + 13 ------------------Then you'll multiply, starting with the right-most term of the lower row, just like in regular (numerical) multiplication:

first multiplication: x^2 - 6x + 9 x^2 + 8x + 13 -------------------- 13x^2 - 78x + 117Then you continue:

second multiplication: x^2 - 6x + 9 x^2 + 8x + 13 ------------------------ 13x^2 - 78x + 117 8x^3 - 56x^2 + 72xThen do the third multiplication, and add down to get your answer.