Question

what is foil??

Answer 1

it is a way of helping you to remember how to expand a binomial.
it stands for first, outside, inside and last.

example
(x + 2)(x - 5)
x and x are the 'first' x*x = x^2
x and -5 are the 'outside' x * -5
+2 and x are the 'inside' +2 * x
+2 and -5 are the 'last' +2 * -5

adding these results gives the expansion

Its just as easy to use the distributive law and first multiply second bracket by and then by +2