Thinking Mathematically (6th Edition)

Published by Pearson
ISBN 10: 0321867327
ISBN 13: 978-0-32186-732-2

Chapter 7 - Algebra: Graphs, Functions, and Linear Systems - 7.3 Systems of Linear Equations in Two Variables - Concept and Vocabulary Check - Page 444: 6

Answer

When solving the given set of equations by addition method, we obtain \[0=3\], so the solution set is empty. If you attempt to solve such a system by graphing, you will obtain two lines that are non-intersecting.

Work Step by Step

Given equations are:\[12x-21y=24\ \text{and }4x-7y=7\]and, \[0=3\]. To eliminate\[x\], second equation is multiplied by\[-3\].Thus, \[\begin{align} & \left( 4x-7y=7 \right)\times -3 \\ & -12x+21y=-21 \\ \end{align}\] Now, add the above new equation to the first equation to eliminate\[x\]as: \[\begin{align} & \left( -12x+21y \right)+\left( 12x-21y \right)=-21+24 \\ & 0=3 \end{align}\] which is not possible, thus the solution set is empty. The graph of the equations show that the lines are non-intersecting, i.e., they don’t have a common solution.
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