Intermediate Algebra for College Students (7th Edition)

Published by Pearson
ISBN 10: 0-13417-894-7
ISBN 13: 978-0-13417-894-3

Chapter 6 - Section 6.5 - Synthetic Division and the Remainder Theorem - Exercise Set - Page 454: 36

Answer

Solution $x=1$. The remainder is zero. $\left \{ -6,-\frac{1}{2},1\right \}$.

Work Step by Step

The given equation is $2x^3+11x^2-7x-6=0$ By using the table the value of $y_1$ is zero at $x=1$ Thus, the solution is $x=1$. The value of $c$ is $1$. Use synthetic division to divide the polynomial $2x^3+11x^2-7x-6$ by $x-c=x-1$. $\begin{matrix} 1) &2&11&-7&-6 \\ & &2&13&6 \\ & --&--&--& --\\ & 2&13&6&0 ​\end{matrix}$ The remainder is zero, which means the solution is correct. The quotient is $2x^2+13x+6$. We can write the given equation in a factor form shown below. $\Rightarrow (x-1)(2x^2+13x+6)=0 $ Rewrite the middle term $13x$ as $12x+1x$. $\Rightarrow (x-1)(2x^2+12x+1x+6)=0 $ Group the terms. $\Rightarrow (x-1)[(2x^2+12x)+(1x+6)]=0 $ Factor each group. $\Rightarrow (x-1)[(2x(x+6)+1(x+6)]=0 $ Factor out $(2x-1)$. $\Rightarrow (x-1)(x+6)(2x+1)=0 $ By using zero product rule set each factor equal to zero. $\Rightarrow x-1=0$ or $x+6=0$ or $2x+1=0 $ Isolate $x$. $\Rightarrow x=1$ or $x=-6$ or $x=-\frac{1}{2} $ The solution set is $\left \{ -6,-\frac{1}{2},1\right \}$.
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