This one's trying to fool you, because the polynomial almost looks like a difference of two squares, but it isn't. How dare it try to pull the wool over our eyes? Doesn't it know it's an open weave anyway? First, we pull out a common factor to get 3(*y*^{2} - 9*x*^{2}). The part in parentheses is a difference of two squares, so it can be written as (*y* + 3*x*)(*y* - 3*x*). To arrive at the final answer, we need to remember to replace the 3 we pulled out. Like you need to remember to replace the roll of toilet paper unless you want your mother screaming at you. Like so: 3(*y* + 3*x*)(*y* - 3*x*). |