 This video will talk about how to determine which is the best way to run an equation. So x squared plus 4x plus 4. I've got three terms. I could use, I could maybe factor, and I could use the quadratic formula. Well, factors of 4 that add up to 4 would be 2 plus 2. So it would factor, but the quadratic formula would also work. When I have a problem like this one, I might be able to factor, but it might take some work because there's some big numbers in there, or I could use the quadratic formula. In other words, we can always use the quadratic formula, even if it doesn't factor. This would be negative 90, and I want to get to negative 5. I can't even think of that off the top of my head, so I probably would try the quadratic formula. In this one, we've got a difference of squares, so that would probably be very easy to do. That would be a very good possibility. In fact, it would probably go a little bit faster than if we did the quadratic formula here. One thing about the quadratic formula here, a is 1, b is there is no x term, so it is 0, and c is negative 81. So you've got to be careful when you don't have a b. The square root property also works here. We could bring the 81 to the other side, and then we'd have x squared equal 81, so x would equal plus or minus 9.