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 - Page 856: 21



Work Step by Step

1. y has opposite signs in the equations. Multiplying the first equation by $4$ and the second by 3 will lead to eliminating y. $\left\{\begin{array}{lll} 8x & -12y & =-28\\ 15x & +12y & =51 \end{array}\right.$ 2. ... add the equations and solve $23x=23\qquad/\div 23$ $x=1$ 3. Back-substitute into one of the initial equations $5x+4y=17$ $5(1)+4y=17$ $5+4y=17\qquad/-5$ $4y=12\qquad/\div 4$ $y=3$ 4. Write the solution as an ordered pair. Solution set: $\{(1,3)\}$
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