How do you FOIL #(x+3)(x+3)(x+3)#?
FOIL will only get you part of the way, since once you multiply one pair of binomials you will have the product of a binomial and a trinomial, but
Using FOIL, first multiply
Add them together:
Alternatively, pick the 4th row of Pascal's triangle to get:
List the first four ascending powers of three:
Multiply these two sequences together to get:
These are the coefficients of the descending powers of