FOIL: multiply First terms, Outside terms, Inside terms, Last terms:
(x+2)(x+2) =x^2 +2x+2x+4 =x^2 +4x+4
(x-2)(x-2) =x^2 -2x-2x +4 =x^2 -4x+4
since these are perfect squares
it is First term squared, double the product of the two terms, Last term squared