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: 15

Answer

$\{(3,-4)\}$

Work Step by Step

1. Express $x$ from the first equation (solve for x). $-2x=6y+18\qquad/\div(-2)$ $x=-3y-9$ 2. Substitute $x$ in the other equation and solve. $-29=5y-3(-3y-9)$ $-29=5y+9y+27\qquad /-27$ $-56=14y\qquad/\div 14$ $-4=y$ $y=-4$ 3. Back-substitute into the expression of $x$ (step 1). $x=-3(-4)-9=12-9=3$ 4. Write the solution as an ordered pair. Solution set: $\{(3,-4)\}$
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