Precalculus (6th Edition)

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

Chapter 1 - Equations and Inequalities - 1.4 Quadratic Equations - 1.4 Exercises - Page 123: 97

Answer

$a=1$ $b=-2$ $c=-1$

Work Step by Step

Given: $ax^{2} + bx + c$ $x=1+\sqrt 2$ $x=1-\sqrt 2$ Use the reverse zero factor property and equate the solns $1+\sqrt 2$ and $1-\sqrt 2$ by 0 $x=1+\sqrt 2$ $x-1-\sqrt 2=0$ $x=1-\sqrt 2$ $x-1+\sqrt 2=0$ Multiply the 2 equations to find the quadratic equation of the solutions $(x+(-1+\sqrt 2))(x+(-1+\sqrt 2))=0$ $x^{2}-2x-1=0$ Notice the similarities of the quadratic equation and identify the values of a, b, and c by just observing the values $ax^{2} + bx + c$ $x^{2}-2x-1=0$ $a=1$ $b=-2$ $c=-1$
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