Big Ideas Math - Algebra 1, A Common Core Curriculum

Published by Big Ideas Learning LLC
ISBN 10: 978-1-60840-838-2
ISBN 13: 978-1-60840-838-2

Chapter 1 - Solving Linear Equations - 1.2 - Solving Multi-Step Equations - Exercises - Page 18: 45

Answer

$x = 0.9375$ Method 1

Work Step by Step

$2(4-8x)+6=-1$ Method $1$: One way to solve the equation is by using the Distributive Property. $$\begin{align*} 2(4-8x)+6&=-1\\ 2(4) - 2(8x)+6&=-1&&\text{Distributive Property}\\ 8 - 16x +6 &=-1&&\text{Multiply}\\ 14- 16x &=-1&&\text{Combine like items}\\ -16x &= -1-14&&\text{Subtract }14\text{ from each side}\\ 16x& =15\\ x&=\frac{15}{16}&&\text{Divide each side by } 16\\ x&=0.9375&&\text{Simplify} \end{align*}$$ Method $2$: Another way to solve the equation is by interpreting the expression $(4-8x)$ as a single quantity. $$\begin{align*} 2(4-8x)+6&=-1\\ 2(4-8x)+6-6&=-1-6&&\text{Subtract }6 \text{ from each side}\\ 2(4-8x)&=-7&&\text{Simplif}\\ \frac{2(4-8x)}{2}& = \frac{-7}{2}&&\text{Divide each side by } 2\\ 4-8x &= -3.5&&\text{Simplify}\\ 4-8x-4 &= -3.5-4&&\text{Subtract }4\text{ from each side}\\ -8x &= -7.5&&\text{Divide each side by }-1\\ 8x &= 7.5&&\text{Divide each side by }8\\ x &= \frac{7.5}{8}&&\text{Simplify}\\ x& = 0.9375 \end{align*}$$ We will prefer the method $1$ as it is very easy and convenient as compared to method $2$.
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