The FOIL Method
Oct 16th, 2009 by Math Tutor NYC
The FOIL Method, which is used to multiply a pair of binomials, is used so often in algebra class, but sometimes it is forgotten when you need it again later on so here’s a quick refresher. First of all, it helps to remember what FOIL stands for:
First
Outer
Inner
Last
First means first terms, outer means outer terms, inner means inner terms, and last means last terms. Let’s take a look at an example. Say you want to multiply (3x + 4) with (2x – 3). The first terms are 3x and 2x. The inner terms are 4 and 2x. The outer terms are 3x and -3. And, the last terms are 4 and -3.
Now, you multiply each of these four pairs of terms together. So, 3x * 2x = 6x^2, 4 * 2x = 8x, 3x * -3 = -9x, and 4 * -3 = -12. If you put that all together you get: 6x^2 + 8x – 9x – 12. You’ll notice the two middle terms can be combined which we’ll do and get: 6x^2 – x – 12.
And, there you go….
(3x + 4) (2x – 3) = 6x^2 – x – 12
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