Precalculus (6th Edition)

Published by Pearson
ISBN 10: 013421742X
ISBN 13: 978-0-13421-742-0

Chapter 3 - Polynomial and Rational Functions - 3.3 Zeros of Polynomial Functions - 3.3 Exercises - Page 337: 66

Answer

$$\color{blue}{ f(x)=x^3-3x^2+2 }$$

Work Step by Step

We are given zeros and asked to write a polynomial function. If $1- \sqrt{3} $ is a zero, then $n +1- \sqrt{3} =0$ $n - \sqrt{3} = -1 $ $n= -1+ \sqrt{3} $ So our factor is $\bf{(x -1+ \sqrt{3} )}$ because when $x= 1- \sqrt{3} $, $(x -1+ \sqrt{3} )=0$ If $ 1+ \sqrt{3} $ is a zero, then $n +1+\sqrt{3} =0$ $n +\sqrt{3} = -1 $ $n= -1-\sqrt{3} $ So our factor is $\bf{(x -1-\sqrt{3} )}$ because when $x= 1+ \sqrt{3} $, $(x -1-\sqrt{3} )=0$ *note that $1- \sqrt{3} $ and $ 1+ \sqrt{3} $ are conjugates If $ 1 $ is a zero, then $n +1 =0$ $n= -1 $ So our factor is $\bf{(x -1 )}$ because when $x= 1 $, $(x -1 )=0$ So our function is: $f(x)=(x -1+ \sqrt{3} ) (x -1-\sqrt{3} ) (x -1 ) $ $f(x)=(x^2-x-x\sqrt{3}-x+1+\sqrt{3}+x\sqrt{3}-\sqrt{3}-3)(x -1) $ $f(x)=(x^2-2x-2)(x-1)$ $f(x)=x^3-x^2-2x^2+2x-2x+2$ $$\color{blue}{ f(x)=x^3-3x^2+2 }$$
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