Elementary Algebra

Published by Cengage Learning
ISBN 10: 1285194055
ISBN 13: 978-1-28519-405-9

Chapter 1 - Some Basic Concepts of Arithmetic and Algebra - 1.1 - Numerical and Algebraic Expressions - Problem Set 1.1: 69

Answer

Your friend is adding $3+2$, before multiplying $2(9)$. You should help him by explaining that in the order of operations, multiplication and division come before addition and subtraction. Use the acronym PEMDAS, Parenthesis, Exponents (and Square Roots), Multiplication/Division, and then Addition/Subtraction.

Work Step by Step

Your friend is solving the equation as if it were like the following: $(3+2)(9)$ $(5)(9)$ $45$ He is solving it as it as if you solve from left to right. However, since there is multiplication, that is done before addition. Therefore, the problem should be solved as such: $3+2(9)$ $3+18$ $21$
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