Precalculus (6th Edition) Blitzer

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

Chapter 2 - Section 2.5 - Zeros of Polynomial Functions - Exercise Set - Page 377: 4

Answer

The possible rational zeroes for the function \[f\left( x \right)=2{{x}^{4}}+3{{x}^{3}}-11{{x}^{2}}-9x+15\] are \[\pm 1,\pm 3,\pm 5,\pm 15,\pm \frac{1}{2},\pm \frac{3}{2},\pm \frac{5}{2},\pm \frac{15}{2}\].

Work Step by Step

Here, the constant term is $15$ and the leading coefficient is 2. The factors of the constant term, $15$ are $\pm 1,\pm 3,\pm 5,\pm 15$ and the factors of the leading coefficient, 2 are $\pm 1,\pm 2$. So, the list of all possible rational zeroes is calculated by the formula: $\begin{align} & \text{Possible rational zeroes}=\frac{\text{Factors of the constant term}}{\text{Factors of the leading coefficient}} \\ & =\frac{\text{Factors of 15}}{\text{Factors of 2}} \\ & =\frac{\pm 1,\pm 3,\pm 5,\pm 15}{\pm 1,\pm 2} \\ & =\pm 1,\pm 3,\pm 5,\pm 15,\pm \frac{1}{2},\pm \frac{3}{2},\pm \frac{5}{2},\pm \frac{15}{2} \end{align}$ Therefore, there are total sixteen possible rational zeroes for the function $f\left( x \right)=2{{x}^{4}}+3{{x}^{3}}-11{{x}^{2}}-9x+15$ that are $\pm 1,\pm 3,\pm 5,\pm 15,\pm \frac{1}{2},\pm \frac{3}{2},\pm \frac{5}{2},\pm \frac{15}{2}$.
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