# What is FOIL and how is it done?

My Algebra teacher was explaining to the class about creating a trinomial using FOIL. What is it, and how is it done?

• Also wiki: Foil Method. Sep 13, 2014 at 22:39
• Forget about Foil, it is for little old school marms, study the distributive law. Sep 13, 2014 at 22:41
• Why was this question down voted? Sep 13, 2014 at 22:47
• I dont know why this was downvoted, but there is a systematic program by a small number of users to downvote and close questions not meeting their "standards". Sep 13, 2014 at 22:52

FOIL is a mnemonic for how to multiply thing in the form $(a+b)*(c+d)$

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

This is you add up the **F**irst terms (ac) , **O**utside terms (ad) , **I**nside terms (bc), and **L**ast terms (bd)

Its just another way to simplify this type of multiplication.

• How is my simple explanation of a simple mnemonic worth 3 upvotes when my more in depth analyses are ignored on other problems? #stackexchangeproblems Sep 13, 2014 at 22:42
• More people can understand the clarity of this explanation.
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Sep 13, 2014 at 22:52
• @mathtastic Thats a good point, but as a reasonably advanced math student, I shall choose to ignore it. Sep 13, 2014 at 22:57
• Did I mention that my highest rated answer of all time has to do with explaining what a percent means? 17 upvotes for that one. Sep 13, 2014 at 23:04
• Welcome to the club! Sep 13, 2014 at 23:15