Precalculus (6th Edition) Blitzer

Published by Pearson
ISBN 10: 0-13446-914-3
ISBN 13: 978-0-13446-914-0

Chapter 2 - Section 2.4 - Dividing Polynomials; Remainder and Factor Theorems - Exercise Set - Page 363: 17

Answer

The value of $\left( 2{{x}^{2}}+x-10 \right)\text{ }\!\!\div\!\!\text{ }\left( x-2 \right)$ is $2x+5$.

Work Step by Step

Consider the provided expression, $\left( 2{{x}^{2}}+x-10 \right)\text{ }\!\!\div\!\!\text{ }\left( x-2 \right)$ Arrange the polynomial in descending powers, with a 0 coefficient for any missing term as shown below, $x-2\overline{\left){2{{x}^{2}}+x-10}\right.}$ Now write 2 for the divisor, $x-2$ to the right and write the coefficients of the dividend as shown below, $\left. {\underline {\, 2 \,}}\! \right| \begin{matrix} 2 & 1 & -10 \\ \end{matrix}$ Now bring down the leading coefficient of the dividend on the bottom row as shown below, $\begin{align} & \left. {\underline {\, 2 \,}}\! \right| \begin{matrix} \text{ }2 & 1 & -10 \\ \end{matrix} \\ & \text{ }\underline{\downarrow \text{Bring down 2}} \\ & \text{ 2} \\ \end{align}$ Multiply 2 with the bottom row value and write the product in the next column in the second row as shown below, $\begin{align} & \left. {\underline {\, 2 \,}}\! \right| \begin{matrix} \text{ }2 & 1 & -10 \\ \end{matrix} \\ & \text{ }\underline{\downarrow \text{ 4}}\text{ } \\ & \text{ 2 } \\ \end{align}$ Add the column values and write down the sum in the bottom row as shown below, $\begin{align} & \left. {\underline {\, 2 \,}}\! \right| \begin{matrix} \text{ }2 & 1 & -10 \\ \end{matrix} \\ & \text{ }\underline{\downarrow \text{ 4}}\text{ } \\ & \text{ 2 5 } \\ \end{align}$ Similarly, repeat this series of multiplications and additions until the columns are filled in, $\begin{align} & \left. {\underline {\, 2 \,}}\! \right| \begin{matrix} \text{ }2 & 1 & -10 \\ \end{matrix} \\ & \text{ }\underline{\downarrow \text{ 4 10}}\text{ } \\ & \text{ 2 5 0} \\ \end{align}$ Thus, the quotient is $2x+5$ and the remainder is $0$.
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