Lesson 18
The Quadratic Formula and Complex Solutions
Lesson Narrative
In the previous lesson, students completed the square to find real and nonreal solutions to quadratic equations. In this lesson, students use the quadratic formula to calculate real and nonreal 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 nonreal 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
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