Question 212189
I recommend what you call "Reversing the FOIL method".  It works very well for most problems.  I call it "Advanced Trinomial Factoring", and my complete explanation of this method is available on my website.  Begin with a "Bing" search for my last name "Rapalje".  Look for "Rapalje Homepage" which is at or near the top of the list.  Then click on the link on my homepage that says "Basic, Intermediate, and College Algebra: One Step at a Time."  Select "Basic Algebra", and look in "Chapter 2" for "Section 2.06, Advanced Trinomial Factoring."  See also my "MATH IN LIVING COLOR" section that pertains to this topic.  It really isn't bad once you understand it.


As for the other method that you mentioned, I have used that method a couple of times in my 40 year career, but it seemed harder for my students, and I never could seem to remember how it worked!  


In addition, I also explained this topic on a video that is available on my website.  From my Homepage, click on the link "Rapalje Videos" and look in "Intermediate Algebra" for the Factoring video.


R^2


Dr. Robert J. Rapalje, Retired
Seminole Community College
Altamonte Springs Campus
Florida