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: 31

Answer

$f(x)=x^{4}-9x^{3}+21x^{2}+21x-130$

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 $(3+2i)$ is a zero, so is $(3-2i).$ $f(x)=a_{n}(x+2)(x-5)(x-3+2i)(x-3-2i)$ $f(x)=a_{n}(x^{2}-3x-10)(x^{2}-3x-2ix-3x+9+6i+2ix-6i-4i^{2})$ $f(x)=a_{n}(x^{2}-3x-10)(x^{2}-6x+13)$ Using the given $f(1),$we find $a_{n}:$ $f(1)=a_{n}(1-3(-1)-10)(1-6(-1)+13)$ $-96=a_{n}(-6)(16)$ $-96=a_{n}(-96)$ $a_{n}=1$ $f(x)=1(x^{2}-3x-10)(x^{2}-6x+13)$ $f(x)=x^{4}-6x+13x^{2}-3x^{3}+18x^{2}-39x-10x^{2}+60x-130$ $f(x)=x^{4}-9x^{3}+21x^{2}+21x-130$
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