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Greatest Common Factors - Problem 3 6,157 views

Teacher/Instructor Alissa Fong
Alissa Fong

MA, Stanford University
Teaching in the San Francisco Bay Area

Alissa is currently a teacher in the San Francisco Bay Area and Brightstorm users love her clear, concise explanations of tough concepts

Okay we’re going to look at some more advanced factoring; in this situation my greatest common factor is going to be a binomial not a monomial. Here is what I mean. I have this problem that’s kind of half factored already. I have this thing that’s already written as a product and this thing’s also already written as a product. If you look at what’s being multiplied to get that each one of these products you’ll get that the greatest common factor. Check it out.

This is 3x times x plus 6. This is -10 times x plus 6 the thing they have in common is the x plus 6. That’s my greatest common factor. It’s kind of tricky because usually our greatest common factors have just been monomials; this is a binomial greatest common factor. Once I know the greatest common factor I want to think about what is being multiplied. This x plus 6 is getting multiplied by 3x and its also being multiplied by -10 so this tricky, tricky, tricky, this answer here is my factor form of this guy and I found it by looking for the binomial that’s the greatest common factor.

This is pretty advanced stuff. It becomes really useful when you start doing what we call factoring by grouping and it might be that you want to revisit this Brightstorm video when you get to the factoring by grouping part of your homework. Just keep in mind sometimes the greatest common factor is not just a monomial, sometimes it’s a binomial like in this situation.