Thinking Mathematically (6th Edition)

Published by Pearson
ISBN 10: 0321867327
ISBN 13: 978-0-32186-732-2

Chapter 6 - Algebra: Equations and Inequalities - 6.5 Quadratic Equations - Exercise Set 6.5 - Page 401: 90

Answer

The factors for the given equation ${{x}^{2}}+6x+8=0$ are $x+2=0$and $x+4=0$, and the values of $x=-4,-2$.

Work Step by Step

The equation is ${{x}^{2}}+6x+8=0$. Below steps to be followed during the method of factorization. Rule 1: Arrange the equation in the decreasing order of power of\[x\] as: ${{x}^{2}}+6x+8=0$ Rule 2: Split the middle term that is term of \[x\]as sum or difference of two terms and the product of these two terms is equal to product of constant and the first term (i.e.,${{x}^{2}}$ ). $\begin{align} & {{x}^{2}}+6x+8=0 \\ & {{x}^{2}}+4x+2x+8=0 \end{align}$ Rule 3: Taking the x common in first two terms and a constant number common in second two terms. $\begin{align} & {{x}^{2}}+6x+8=0 \\ & {{x}^{2}}+4x+2x+8=0 \\ & x\left( x+4 \right)+2\left( x+4 \right)=0 \\ & \left( x+2 \right)\left( x+4 \right)=0 \end{align}$ These are the obtained factors for the given equation. Rule 4: Equating each factor to zero as: $\begin{align} & x+2=0 \\ & x+4=0 \end{align}$ The values of\[x\]or roots of equation are $x=-4,-2$. The factors for the given equation ${{x}^{2}}+6x+8=0$ are $x+2=0$and $x+4=0$, and the values of $x=-4,-2$.
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