Lesson 17
Applying the Quadratic Formula (Part 1)
Lesson Narrative
In this lesson, students return to some quadratic functions they have seen. They write quadratic equations to represent relationships and use the quadratic formula to solve problems that they did not previously have the tools to solve (other than by graphing). In some cases, the quadratic formula is the only practical way to find the solutions. In others, students can decide to use other methods that might be more straightforward (MP5).
The work in this lesson—writing equations, solving them, and interpreting the solutions in context—encourages students to reason quantitatively and abstractly (MP2).
Learning Goals
Teacher Facing
 Interpret (orally and in writing) the solutions to quadratic equations in context.
 Practice using the quadratic formula to solve quadratic equations, rearranging the equations into $ax^2+bx+c=0$ if not already given in this form.
Student Facing
 Let’s use the quadratic formula to solve some problems.
Required Materials
Learning Targets
Student Facing
 I can use the quadratic formula to solve an equation and interpret the solutions in terms of a situation.
CCSS Standards
Glossary Entries

quadratic formula
The formula \(x = {\textb \pm \sqrt{b^24ac} \over 2a}\) that gives the solutions of the quadratic equation \(ax^2 + bx + c = 0\), where \(a\) is not 0.