Precalculus (6th Edition)

Published by Pearson
ISBN 10: 013421742X
ISBN 13: 978-0-13421-742-0

Chapter 9 - Systems and Matrices - 9.1 Systems of Linear Equations - 9.1 Exercises: 13

Answer

$\{(-1,3)\}$

Work Step by Step

1. Express y from the first equation (solve for y) $7x-y=-10\qquad/+y-10$ $7x-10=y$ $y=7x+10$ 2. Substitute y in the other equation and solve. $3(7x+10)-x=10$ $21x+30-x=10\qquad/-30$ $20x=-20\qquad/\div 20$ $x=-1$ 3. Back-substitute into the expression of y (step 1). $y=7(-1)+10=3$ 4. Write the solution as an ordered pair. Solution set: $\{(-1,3)\}$
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