## Algebra 1

Published by Prentice Hall

# Chapter 6 - Systems of Equations and Inequalities - 6-4 Application of Linear Systems - Practice and Problem-Solving Exercises - Page 387: 15

#### Answer

The most efficient method to solve this system is substitution because we can easily substitute the value of y, given by the second equation, into the first equation . The solution is: (-3,-2)

#### Work Step by Step

Our two systems are: 1. 2x+7y=-20 2. y=3x+7 Lets substitute the second equation into the first equation for y. 2x+7(3x+7)=-20. (Distribute the 7) 2x+21x+49=-20. (Simplify) 23x+49=-20 (Subtract 49 from both sides) 23x=-69. (Divide by 23 on both sides) x=-3 Now that we know the value of x, lets substitute it into the second equation to find the value of y. y=3(-3)+7. (Simplify) y=-2 So by using substitution, we got our answer to be: (-3,-2)

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