Algebra 2 Common Core

Published by Prentice Hall
ISBN 10: 0133186024
ISBN 13: 978-0-13318-602-4

Chapter 1 - Expressions, Equations, and Inequalities - 1-3 Algebraic Expressions - Practice and Problem-Solving Exercises: 55

Answer

He can't remove the first set of parenthesis if there is a negative sign in front of it. Also, he distributed incorrectly in the second part of the problem.

Work Step by Step

When there is a negative sign in front of parenthesis, you can remove the parenthesis by distributing -1 to the terms inside of the parenthesis. Therefore, $-(x+y)=-x-y$. Also, he didn't distribute the 3 correctly. $3(x-4y)=3x-12y$. The correct answer is $-x-y+3x-12y=2x-13y$.
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