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 2 - Equations, Inequalities, and Problem Solving - 2.2 Using the Principles Together - 2.2 Exercise Set - Page 94: 55



Work Step by Step

$\bf{\text{Solution Outline:}}$ To solve the given equation, $ 2.1x+45.2=3.2-8.4x ,$ remove first the decimal numbers by multiplying both sides by a power of $10.$ Then use the properties of equality to isolate the variable. Do checking of the solution. $\bf{\text{Solution Details:}}$ Since the largest number of decimal places a term has is $1,$ multiply both sides by $10.$ This results to \begin{array}{l}\require{cancel} 2.1x+45.2=3.2-8.4x \\\\ 10(2.1x+45.2)=10(3.2-8.4x) \\\\ 21x+452=32-84x .\end{array} Using the properties of equality to isolate the variable, the equation above is equivalent to \begin{array}{l}\require{cancel} 21x+452=32-84x \\\\ 21x+84x=32-452 \\\\ 105x=-420 \\\\ x=\dfrac{420}{105} \\\\ x=-4 .\end{array} Checking: If $x=-4,$ then \begin{array}{l}\require{cancel} 2.1(-4)+45.2=3.2-8.4(-4) \\\\ -8.4+45.2=3.2+33.6 \\\\ 36.8=36.8 \text{ (TRUE) } .\end{array} Hence, the solution is $ x=-4 .$
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