Lesson 20

Rational Equations (Part 1)

Lesson Narrative

In previous lessons, students studied rational functions. They made sense of graphs in context, learned about asymptotes, and rewrote expressions to reveal end behavior. The goal of this lesson is for students to write rational equations to model simple situations, such as average cost and batting averages, and then use their equations to answer questions and interpret the meaning of their answer in context (MP2) while making use of the structure of rational equations (MP7).

This is the first of three lessons on solving rational equations. In this lesson, students write and solve equations involving a rational expression that is equal to a rational number. As the lessons progress, students will solve increasingly challenging rational equations, with the third lesson focusing on understanding how extraneous solutions may arise.

Technology isn’t required for this lesson, but there are opportunities for students to choose to use appropriate technology to solve problems. We recommend making technology available.

Learning Goals

Teacher Facing

  • Calculate solutions to equations involving a single rational expression.
  • Create simple equations involving a rational expression to solve a problem in context.

Student Facing

  • Let’s write and solve some rational equations.

Learning Targets

Student Facing

  • I can write rational expressions that represent averages to answer questions about the situation.

CCSS Standards

Building On

Addressing

Building Towards