 This video is called solve trinomials by factoring two, so we know that we have to factor it and then set everything equal to zero so I can see where this polynomial, which is a parabola, see where it crosses the x-axis on a graph. Before I start factoring though I recognize I can take out a GCF. I can pull out a two. So I have an x squared plus 3x minus four left. So now that I'm ready to factor, I've just made it a lot easier and simpler on myself to see what multiplies to give me negative four and adds to give me positive three. Well four is a four and one or a two and two. I think a positive four and a negative one can add to give me a positive three and a positive four times a negative one can multiply to give me negative four. So, oops, I continue on with my two parentheses. Don't forget to bring down the two and the equals zero. I'll split up my x. I'll put the plus four in one parentheses, the minus one in the other and now I remember I've got three terms to set equal to zero. Two equals zero, x plus four equals zero, x minus one equals zero. Well two will never equal zero, so I can get rid of that choice or that option. Here, when I subtract four from both sides, I get x equals negative four and when I add one, I get x equals one. So those are my answers, but just to make sure you understand what's going on, remember if you were going to put these on a graph, at one and negative four is where this parabola would cross the x-axis. So we'd have a sketch like that. The second problem for this video, again, we want to solve trinomials by factoring, but I notice this is not in the right format to solve. I need to get all my terms on the left-hand side of the equal sign. So I'm going to add 24 to both sides. So I get x squared minus 25x plus 24 equals zero. Can I take out a GCF? No, because I don't have an x in all three terms and I don't have a number bigger than one in all three terms that I can factor out. So we'll start by thinking about what multiplies to give us a positive 24 and adds to give us a negative 25. Well, product, or factors of 24 are 24 and 1, 12 and 2, 8 and 3, 6 and 4. Which set will multiply to give me a positive 24 and add to give me a negative 25? Well, a negative 24 plus a negative 1. So I make my two parentheses. I don't forget to bring down my equals zero. I've got x minus 24 and x minus 1. So it looks like I have two different terms. I've got to split it up and set them equal to zero. So I'm going to add 24. So I have x equals 24 and I'm going to add 1. So I have x equals 1. So if I were going to graph this, I would know that my problem, my u-shape would cross the x-axis way out at 24 and at 1.