## Elementary Technical Mathematics

Published by Brooks Cole

# Chapter 9 - Section 9.2 - Solving Pairs of Linear Equations by Addition - Exercises - Page 332: 1

(2,1)

#### Work Step by Step

Add the 2 equations. Align and add the like terms. $3x+y=7$ $\underline{\ \ x-y=1}$ $4x\ \ \ \ \ \ \ =8\ \ \longrightarrow$ Divide both sides by 4 to solve for x. $\ \ x\ \ \ \ \ \ \ =2$ Substitute 2 for x in one of the equations to solve for y. $x-y=1\longrightarrow$ substitute for x $2-y=1\longrightarrow$ add y to each side; subtract 1 from each side $2-y+y-1=1+y-1\longrightarrow$ combine like terms $1=y$

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