# Quadratic Inequalities | Algebra | Maths | FuseSchool

Click here to see more videos: https://alugha.com/FuseSchool CREDITS Animation & Design: Jean-Pierre Louw - www.behance.net/Appel718 Narration: Lucy Billings Script: Lucy Billings You probably already know that quadratic equations look like this. We can also have quadratic inequalities. We use inequalities to show us a range of possible values, which actually has many real-life uses. For example, I might use them to work out that I need to film a race car between 10 and 15 seconds after the start of the race. And they’re used throughout finance, such as working out what loan you can afford based on your expenditure. We solve quadratic inequalities in pretty much the same way we solve quadratic equations, but also making use of the graph to help us work out which part we want. Let’s have a look at an example. Solve it like you normally would, so factorize, quadratic formula, or complete the square. This one factorizes. Notice how I’ve changed it to be equals. Solve each bracket, x equals 3, and x equals negative 2. Sketch what this quadratic looks like. It is U shaped, crossing the x-axis at -2 and 3. It’s just a rough sketch to help yourself in answering the question, so don’t worry too much about it at all. Because we want where the quadratic is less than 0, we want this part of the graph. The part that is less than 0 for y, but also has the quadratic in. This means the answer is x is greater than or equal to negative 2, but less than or equal to 3. Because we’ve shaded one joined region, the answer is one inequality. It’s this inequality sign because that was in the question. Because we have 2 separate regions shaded, this means we have 2 separate inequality answers. Where x is less than negative 4, and where x is greater than negative 2. Because the question was a “greater than” inequality, that’s what our answers are. There is no “or equal to” involved. And that’s all there is to solving quadratic inequalities. You just need to do a little sketch of the graph and work out the values from there. VISIT us at www.fuseschool.org, where all of our videos are carefully organised into topics and specific orders, and to see what else we have on offer. Comment, like and share with other learners. You can both ask and answer questions, and teachers will get back to you. Access a deeper Learning Experience in the FuseSchool platform and app: www.fuseschool.org This Open Educational Resource is free of charge, under a Creative Commons License: Attribution-NonCommercial CC BY-NC ( View License Deed: http://creativecommons.org/licenses/by-nc/4.0/ ). You are allowed to download the video for nonprofit, educational use. If you would like to modify the video, please contact us: info@fuseschool.org