Precalculus: Mathematics for Calculus, 7th Edition

Published by Brooks Cole
ISBN 10: 1305071751
ISBN 13: 978-1-30507-175-9

Chapter 3 - Section 3.5 - Complex Zeros and the Fundamental Theorem of Algebra - 3.5 Exercises - Page 294: 38

Answer

$P(x)=x^{2}-2x+3$

Work Step by Step

The degree is 2, there are 2 complex zeros, $(1+i\sqrt{2})$ and $(1-i\sqrt{2})$ are conjugates, $[x-(1+i\sqrt{2})]$ and $[x-(1-i\sqrt{2})] $are factors, $(x-1-i\sqrt{2})$ and $(x-1+i\sqrt{2}) $are factors. So, $P(x)=a(x-1-i\sqrt{2})(x-1+i\sqrt{2})$ ... taking $a=1$, ... applying a difference of squares, $P(x)=[(x-1)-i\sqrt{2}][(x-1)+i\sqrt{2}]$ $=(x-1)^{2}-(i\sqrt{2})^{2}$ ... apply a square of a difference and $(i^{2}=-1)$ $=x^{2}-2x+1-2(-1)$ $=x^{2}-2x+3$ $P(x)=x^{2}-2x+3$
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