Posted by Anonymous on Sunday, February 17, 2013 at 4:18am.
You might want to look at the patterns of "trinomial expansion" and its connection to Pascal's triangle
Here is a very neat webpage.
They expand (a+b+c)^5
You have to expand (a+b+c)^4
http://www.rowan.edu/open/depts/math/osler/Trinomial_triangle.pdf