## Algebra 1

Published by Prentice Hall

# Chapter 1 - Foundations for Algebra - 1-8 An Introduction to Equations - Lesson Check - Page 56: 6

#### Answer

Mental math is preferred because the equation is simple enough to easily solve with mental math. Creating the table takes more time than mental math in this case. x=9

#### Work Step by Step

Use mental math. What number can be added to 4 to equal 13? $9+4=13$ You can use a table to find the value. $\underline{x}\ \ \ \ \underline{x+4}$ $1\ \ \ \ \ \ \ \ 5$ $2\ \ \ \ \ \ \ \ 6$ $3\ \ \ \ \ \ \ \ 7$ $4\ \ \ \ \ \ \ \ 8$ $5\ \ \ \ \ \ \ \ 9$ $6\ \ \ \ \ \ \ \ 10$ $7\ \ \ \ \ \ \ \ 11$ $8\ \ \ \ \ \ \ \ 12$ $9\ \ \ \ \ \ \ \ 13\longrightarrow$ the solution is 9

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