College Algebra (6th Edition)

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

Chapter 3 - Summary, Review, and Test - Review Exercises - Page 436: 17

Answer

x = $-5$, multiplicity $1$, crosses the x-axis x = $5$, multiplicity $2$, touches the x-axis and turns

Work Step by Step

Multiplicity and x-intercepts (page 354): If $(x-r)$ appears k times in a full factorization of f(x), then r is a zero with multiplicity k. If $r$ is a zero of even multiplicity, then the graph touches the x-axis and turns around at $r$. If $r$ is a zero of odd multiplicity, then the graph crosses the x-axis at $r$. ---------- Factor the expression of f(x): $ f(x)=x^{3}-5x^{2}-25x+125\qquad$ ... factor in pairs $f(x)=x^{2}(x-5)-25(x-5)$ $ f(x)=(x-5)(x^{2}-25)\qquad$ ... recognize a difference of squares $f(x)=(x-5)(x-5)(x+5)$ $f(x)=(x-5)^{2}(x+5)$ Zeros: x = $-5$, multiplicity $1$, (odd), crosses the x-axis x = $5$ multiplicity $2$, (even), touches the x-axis and turns
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