Algebra 2 Common Core

Published by Prentice Hall
ISBN 10: 0133186024
ISBN 13: 978-0-13318-602-4

Chapter 5 - Polynomials and Polynomial Functions - 5-6 The Fundamental Theorem of Algebra - Practice and Problem-Solving Exercises - Page 324: 55

Answer

The solutions are $x = 3 - 2\sqrt {2}$ and $x = 3 + 2\sqrt {2}$.

Work Step by Step

We are asked to use the quadratic formula to factor this polynomial. The quadratic formula is given by: $x = \dfrac{-b \pm \sqrt {b^2 - 4ac}}{2a}$ where $a$ is the coefficient of the $x^2$ term, $b$ is the coefficient of the $x$ term, and $c$ is the constant. We have $a=1, b=-6,$ and $c=1$ so substituting them into the formula gives:: $x = \dfrac{-(-6) \pm \sqrt {(-6)^2 - 4(1)(1)}}{2(1)}$ $x = \dfrac{6 \pm \sqrt {36 - 4}}{2}$ $x = \dfrac{6 \pm \sqrt {32}}{2}$ The number $32$ can be factored as $16(2)$ so: $x = \dfrac{6 \pm \sqrt {(16)(2)}}{2}$ We bring out the square root of $16$ which is $4$, so we have: $x = \dfrac{6 \pm 4\sqrt {2}}{2}$ Divide both numerator and denominator by $2$ to obtain: $x = 3 \pm 2\sqrt {2}$ Thus, the solutions are $x = 3 ± 2\sqrt {2}$.
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