Precalculus: Mathematics for Calculus, 7th Edition

Published by Brooks Cole
ISBN 10: 1305071751
ISBN 13: 978-1-30507-175-9

Chapter 3 - Review - Test - Page 323: 6

Answer

(a) $\frac{p}{q}=\pm1,\pm\frac{1}{2},\pm3,\pm\frac{3}{2}$ (b) $P(x)=(x-3)(2x-1)(x+1)$ (c) $-1, \frac{1}{2}, 3$ (d) see plot.

Work Step by Step

We have $P(x)=2x^3-5x^2-4x+3$ (a) $p=\pm1,\pm3,q=\pm1,\pm2$, possible rational zeros: $\frac{p}{q}=\pm1,\pm\frac{1}{2},\pm3,\pm\frac{3}{2}$ (b) Use synthetic division, find one zero of P and the quadratic form: $P(x)=(x-3)(2x^2+x-1)=(x-3)(2x-1)(x+1)$ (c) The zeros of P are $-1, \frac{1}{2}, 3$ (d) The y-intercept is $P(0)=3$. End behaviors: when $x\to -\infty, y\to -\infty$; when $x\to \infty, y\to \infty$ Test points $P(1)=-4,P(2)=-9$ Use the above information to plot the function.
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