This week we learned how to factor a difference of squares, for example – = (a – b) (a + b) for a difference of squares to be a difference of squares, both sides must be… squares, perfect squares.  so if we have + we can square root it and we`ll have ( x – 3y) (x + 3y) the first bracket is subtraction and the second one is additon and if its a difference of squares it must have both. And that`s how you factor a difference of squares