Lesson 18

The Quadratic Formula and Complex Solutions

Lesson Narrative

In the previous lesson, students completed the square to find real and non-real solutions to quadratic equations. In this lesson, students use the quadratic formula to calculate real and non-real solutions.

Students construct viable arguments and critique the reasoning of others when they compare solutions of equivalent quadratic equations and resolve any disagreements during a row game (MP3).

Learning Goals

Teacher Facing

  • Calculate complex solutions using the quadratic formula and represent them in the form $c \pm di$, where $c$ and $d$ are real numbers.
  • Explain reasoning and critique the reasoning of others when solving quadratic equations.
  • Explain when solutions are non-real when using the quadratic formula.

Student Facing

  • Let’s use the quadratic formula to find complex solutions to quadratic equations.

Learning Targets

Student Facing

  • I can find complex solutions to quadratic equations by using the quadratic formula.

CCSS Standards

Building On


Building Towards

Print Formatted Materials

Teachers with a valid work email address can click here to register or sign in for free access to Cool Down, Teacher Guide, and PowerPoint materials.

Student Task Statements pdf docx
Cumulative Practice Problem Set pdf docx
Cool Down Log In
Teacher Guide Log In
Teacher Presentation Materials pdf docx

Additional Resources

Google Slides Log In
PowerPoint Slides Log In