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: 24

Answer

$\{(2,3)\}$

Work Step by Step

1. The least work in creating opposite coefficients is to multiply the second equation by ($-4)$ , which will lead to eliminating x $\left\{\begin{array}{lll} 12x & -5y & =9\\ -12x & +32y & =72 \end{array}\right.$ 2. ... add the equations and solve $27y=81\qquad/\div 27$ $y=3$ 3. Back-substitute into one of the initial equations $3x-8y=-18$ $3x-8(3)=-18$ $3x-24=-18\qquad/+24$ $3x=6\qquad/\div 3$ $x=2$ 4. Write the solution as an ordered pair. Solution set: $\{(2,3)\}$
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