 In this video we're going to discover what the difference of two squares means and how to factorize these special quadratics. Before we get started, make sure you know your square numbers. You should recognize that any expressions like this are quadratics because the x squared is the highest power of x. So these are both quadratics, but these are also quadratics. They only have an x squared term and a number. These special quadratics can still be factorized by spotting that it's the difference of two squares. Both the x squared and the nine are square numbers. These are really simple to factorize. The square root of nine is three, so both of our brackets are threes. Because there isn't an x term in these special quadratics, one bracket needs to be a plus and the other a minus. By having one plus and one minus, when we expand the brackets, this will eliminate the x term completely, leaving us with just an x squared minus a number. One key thing to note is that we can only factorize like this when it's an x squared minus a square number. It must be a minus, not a plus. So here are two for you to factorize. Pause the video, factorize and click play when you're ready. Did you get them right? Did you get the second one right? It's still the difference of two squares, but you just put the numbers first and the x's second. So how do you think we factorize this one? Four and one hundred are both square numbers, so we do the exact same thing. But instead of x, we need to do two x, because the square root of four is two. Simple. Two more questions for you to do. Pause the video, factorize and click play when you're ready. Did you get them right? So that's the difference of two squares. A squared x squared, a square number and a minus.