Precalculus (6th Edition) Blitzer

Published by Pearson
ISBN 10: 0-13446-914-3
ISBN 13: 978-0-13446-914-0

Chapter 7 - Test - Page 879: 2


The solution of the system is $\underline{\left( 4,-2 \right)}$

Work Step by Step

Let us consider the system of the given equations: $2x+5y=-2$ (I) $3x-4y=20$ (II) Multiply equation (I) with 4 and thus obtain $8x+20y=-8$ (III) Multiply equation (II) with 5 and thus obtain $15x-20y=100$ (IV) Add equations (III) and (IV) as follows: $\begin{align} & 8x+20y+15x-20y=-8+100 \\ & 23x=92 \\ & x=\frac{92}{23} \\ & x=4 \end{align}$ Put the value of x in equation (I), to obtain the value of y as shown below: $\begin{align} & 2\left( 4 \right)+5y=-2 \\ & 8+5y=-2 \\ & 5y=-10 \\ & y=-2 \end{align}$ Thus, the values are $ x=4$ and $ y=-2$.
Update this answer!

You can help us out by revising, improving and updating this answer.

Update this answer

After you claim an answer you’ll have 24 hours to send in a draft. An editor will review the submission and either publish your submission or provide feedback.