Expert: Wei Chong - 5/15/2008

Question
Okay, why do we use the FOIL method in math anyways? What does it help us
with?

Answer
Hi Anna,

The FOIL method is used when we multiply two binomials. From your question, I got an impression that you already know how to use FOIL method. So, let me explain why we need to use it.

Let's start from the basics:

You should have came across the Distributive Property before. For example, we need to use this property when we simplify the following expression:

                         3(x+1)

Using the Distributive Property, we have:

           3(x+1) = 3x + 3

You can find out the explanation behind this from the math video at the following:

http://www.mathexpression.com/simplifying-algebraic-expressions.html

Now, when the expression becomes more complicated. Such as:

          (a + b)(c + d)

We can simplify the above expression using the basics that we have learned above by:

           (a + b)(c + d)
           = a(c + d) + b(c + d)   ---Step 1
           = ac + ad + bc + bd     ---Step 2     
        
Now, the above method requires 2 steps to solve. But, by using the FOIL method, we can immediately skip Step 1 and quickly arrive at the answer (Step 2).

              (a + b)(c + d)
               = ac + ad + bc + bd

What's the benefit of doing so? First, you save time. Second, less steps means less chance of making mistakes.

Hope this helps.