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---TRANSCRIPT---
Thanks for stopping by. This is 2 Minute Classroom and today we are talking about how to multiply binomials, like these, using the FOIL method.
You’ll use the FOIL method to turn two binomials like these... into their quadratic polynomial or standard form, like so...
FOIL stands for
First
Outer
Inner
Last
...but you probably already knew that.
You use it to multiply each term in one expression by each term in the other expression.
Let’s work through a few examples:
We’ll start simple: multiply (x+2) by (2x+3).
We start by multiplying the first two terms together. So x times 2x equals 2x squared.
Next we multiply the outer terms x times 3 equals 3x.
Then we multiply the inner terms together. 2 times 2x gives us 4x.
And finally we multiply the last two terms together. 2 times 3 gives us 6.
Now we have the equation 2x squared +4x+3x+6.
All that is left to do is combine like terms, in this case the sum of 4x and 3x which gives us 7x. So we end up with the polynomial 2x squared +7x+6.
Simple right? But there are some tricky questions you may encounter. For example, if you're asked to solve the expression (3x+4) squared, what do you do?
First, you split the equation into two binomials, so (3x+4) times (3x+4). Then you just use the FOIL method.
First…
Outer…
Inner…
Notice the outer and the inner products are the same when you're solving for a square.
And last…
This gives you 9x squared +12x12x+16
Then combine like terms, and you should end up with 9x squared +24x+16.
Another tricky situation is when negative numbers are involved in your binomials.
For example, (x+1)(2x-3). Don’t panic, just use the FOIL method and whenever you use this 3, it should always be negative.
Real quick,
First…
Outer...
Inner...
Last…
Put them together to get 2x squared -3x+2x-3
And combine like terms to get the polynomail 2x squared -x-3.
If you have any tests or quizzes coming up in any of your classes you’ll want to watch my test prep playlist. Or watch this video that YouTube thinks you’ll enjoy.
Thanks for watching, and I’ll catch you next time.
