College Algebra (6th Edition)

Published by Pearson
ISBN 10: 0-32178-228-3
ISBN 13: 978-0-32178-228-1

Chapter 3 - Mid-Chapter Check Point - Page 390: 15

Answer

$x\displaystyle \in\left\{\frac{1}{3},\frac{1}{2},1\right\}$

Work Step by Step

See The Rational Zero Theorem: If $\frac{p}{q}$ is a zero of the polynomial $f(x) $with integer coefficients, then $p$ is a factor of the constant term, $a_{0}$, and $q$ is a factor of the leading coefficient, $a_{n}$. ------------------------ $6x^{3}-11x^{2}+6x-1=0$ a. Candidates for zeros, $\frac{p}{q}:$ $p:\qquad \pm 1 $ $q:\qquad \pm 1, \pm 2, \pm 3, \pm 6$ $\displaystyle \frac{p}{q}:\qquad \pm 1, \pm\frac{1}{2},\pm\frac{1}{3}, \pm\frac{1}{6}$ b. Try for $x=1:$ $\begin{array}{lllll} \underline{1}| & 6 & -11 & 6 & -1\\ & & 6 & -5 & 1\\ & -- & -- & -- & --\\ & 6 & -5 & 1 & |\underline{0} \end{array}$ $1$ is a zero, $(x-1)(6x^{2} -5x+1)$ c. Factorize the trinomial factor $(6x^{2} -5x+1)$ $6x^{2} -5x+1=6x^{2} -3x-2x+1 \quad$...factor in pairs ... $=3x(2x-1)-1(2x-1)=(2x-1)(3x-1)$ $(x-1)(2x-1)(3x-1)=0$ $x\displaystyle \in\left\{\frac{1}{3},\frac{1}{2},1\right\}$
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