Precalculus: Concepts Through Functions, A Unit Circle Approach to Trigonometry (3rd Edition)

Published by Pearson
ISBN 10: 0-32193-104-1
ISBN 13: 978-0-32193-104-7

Chapter 3 - Polynomial and Rational Functions - Section 3.3 Complex Zeros; Fundamental Theorem of Algebra - 3.3 Assess Your Understanding - Page 231: 19

Answer

$x^5-4x^4+7x^3-8x^2+6x-4$

Work Step by Step

The Conjugate Pairs Theorem states that when a polynomial has real coefficients, then any complex zeros occur in conjugate pairs. This means that, when $(p +i \ q)$ is a zero of a polynomial function with a real number of the coefficients, then its conjugate $(p –i q)$, is also a zero of the function. We are given that the zeros of the function are: $2, 1\pm i, \pm i$ . We write the factors of the function as $(x-zero)$ and multiply them to get the polynomial. Therefore, we can write the equation of the function as: $f(x)=[x-(1+i)][x-(1-i)](x-i)(x-(-i)) (x-2) \\=(x-1-2i)(x-1+i)(x-i)(x+i)(x-2)\\=x^5-4x^4+7x^3-8x^2+6x-4$
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