This is the theorem that I use, so to expand, you multiply the first number in the equation so it would be w times w because in (w-9) and (w+3) w is the first term. So now you do the outer number which is the first and last number in the equation which is w and 3 and we multiply them together. now we do the inner, which are the two inner terms, which are -9 and w and we multiply them. Now we do the last terms in each ( ) which is -9 and 3 and we multiply them. This is kinda hard to get used to, but it helps so much when you are trying to expand trinomials that are multiplied together!
so we add all the answers we got for first, outer, inner and last numbers
