Education Technology

Extraneous Solutions

Activity Overview

Students will solve quadratic equations step by step graphically. They will discover that some of the equations have an extraneous solution and they will investigate at which step in solving the equation that these extra solutions appear.

Key Steps

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    You may wish to work though this problem with students if they are unfamiliar with solving equations graphically. Students will be moving back and forth between pages 1.3 and 1.4 to access the equations and then the graph. Encourage them to write the solution(s)—i.e., the x‑coordinates of the point(s) of intersection of functions f1 and f2 - on their worksheet.