Some important relationships are not linear—those based on gravity, on area or volume, even equations that predict the best selling price for a product. Skydivers, painters, astronauts, and retailers all use a class of functions called quadratic, from the Latin word meaning, "to make a square."

In this chapter you will: build on your knowledge of systems of equations and inequalities learned in Chapter 6 learn to solve quadratic equations and functions use quadratic equations to solve real-world problems learn to find square roots and graph quadratic functions solve quadratic equations using the quadratic formula use the discriminant to find the number of solutions of a quadratic equation