Summary
  1. find two terms that multiply to get the last term and add to get the middle term.
  2. set both terms equal to the variable.
  3. put both answers back into the equation to see which, if both, work.

Link to Video:
http://www.pascack.k12.nj.us/cms/lib5/NJ01000238/Centricity/Domain/87/MayaProject.mov

Below is a tutorial website:
http://www.regentsprep.org/regents/math/algebra/AV6/Ltri1.htm