College Algebra (6th Edition)

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

Chapter 3 - Polynomial and Rational Functions - Exercise Set 3.4 - Page 387: 28

Answer

$f(x)=3x^{3}+12x^{2}-93x-522$

Work Step by Step

The Linear Factorization Theorem... in words: An nth-degree polynomial can be expressed as the product of a nonzero constant and $n$ linear factors, where each linear factor has a leading coefficient of 1. Imaginary roots, if they exist, occur in conjugate pairs. ------------------------- If $(-5+2i)$ is a zero, so is $(-5-2i).$ $f(x)=a_{n}(x-6)(x+5+2i)(x+5-2i)$ $f(x)=a_{n}(x-6)(x^{2}+5x-2ix+5x+25-10i+2ix+10i-4i^{2})$ ...$ i^{2}=-1$ ... $f(x)=a_{n}(x-6)(x^{2}+10x+29)$ Using the given $f(2),$we find $a_{n}:$ $f(2)=a_{n}(2-6)(4+20+29)$ $-636=a_{n}(-4)(53)$ $-636=a_{n}(-212)$ $a_{n}=3$ $f(x)=3(x-6)(x^{2}+10x+29)$ $f(x)=3(x^{3}+10x^{2}+29x-6x^{2}-60x-174)$ $f(x)=3(x^{3}+4x^{2}-31x-174)$ $f(x)=3x^{3}+12x^{2}-93x-522$
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