Elementary and Intermediate Algebra: Concepts & Applications (6th Edition)

Published by Pearson
ISBN 10: 0-32184-874-8
ISBN 13: 978-0-32184-874-1

Chapter 8 - Systems of Linear Equations and Problem Solving - 8.2 Solving by Substitution or Elimination - 8.2 Exercise Set - Page 516: 19



Work Step by Step

Isolate $t$ in eq.$1$ $-5s+t=11\qquad$ ... add $5s$ $t=11+5s\qquad $(*) Replace $t$ with $11+5s$ in the other equation: $ 4s+12(11+5s)=4\qquad$ ... and solve for $s$. Simplify $4s+132+60s=4$ $ 64s+132=4\qquad$ ... subtract 132 $ 64s=-128\qquad$ ... divide with $64$ $s=-2$ Now, back-substitute into (*) $t=11+5(-2)=11-10=1$ Form an ordered pair $(s,t) $ as the solution to the system $(-2,1)$
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