Precalculus (10th Edition)

Published by Pearson
ISBN 10: 0-32197-907-9
ISBN 13: 978-0-32197-907-0

Appendix A - Review - A.3 Polynomials - A.3 Assess Your Understanding - Page A30: 70

Answer

Quotient $=x^2-\dfrac{2x}{3}-\dfrac{1}{9}$ Remainder $=\dfrac{16x-17}{9}$

Work Step by Step

The given expression is $(3x^4-x^3+x-2)\div(3x^2+x+1)$ Rewrite the expression as $(3x^4-x^3+0x^2+x-2)\div(3x^2+x+1)$ Perform long division: $\begin{matrix} & x^2 & -2x/3 & -1/9 ​& & && \leftarrow &\text{Quotient}\\ &-- &-- &--&--& \\ 3x^2+x+1) &3x^4&-x^3&+0x^2&+x&-2 & \\ ​& 3x^4 &+x^3 & +x^2& &&& \leftarrow &x^2(3x^2+x+1) \\ & -- & -- & --& &&&\leftarrow &\text{subtract} \\ & 0 & -2x^3& -x^2 &+x & & \\ ​& &-2x^3 & -2x^2/3&-2x/3 &&& \leftarrow &-2x/3(3x^2+x+1) \\ & & -- & --& -- &&&\leftarrow &\text{subtract} \\ & & 0 & -x^2/3& +5x/3 &-2 & & \\ ​& &&-x^2/3 & -x/9&-1/9 && \leftarrow &-1/9(3x^2+x+1) \\ & && -- & --& -- &&\leftarrow &\text{subtract} \\ & && 0 & +16x/9 & -17/9 & & \leftarrow & \text{Remainder} ​\end{matrix}$ Checking: $\text{(Quotient)(divisor)+ Remainder}$ $=(x^2-\frac{2x}{3}-\frac{1}{9})(3x^2+x+1)+\frac{16x}{9}-\frac{17}{9}$ $=3x^4-2x^3-\frac{x^2}{3}+x^3-\frac{2x^2}{3}-\frac{x}{9}+x^2-\frac{2x}{3}-\frac{1}{9}+\frac{16x}{9}-\frac{17}{9}$ $=3x^4-x^3+x-2$ $=\text{ Dividend}$ Hence, the quotient is $x^2-\frac{2x}{3}-\frac{1}{9}$ and the remainder is $\frac{16x}{9}-\frac{17}{9}$.
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