Functions Modeling Change: A Preparation for Calculus, 5th Edition

Published by Wiley
ISBN 10: 1118583191
ISBN 13: 978-1-11858-319-7

Chapter 3 - Quadratic Functions - 3.1 Introduction to the Family of Quadratic Functions - Exercises and Problems for Section 3.1 - Exercises and Problems - Page 121: 11

Answer

a) The solutions are $x \approx 0.057 $ and $x \approx 1.943$ b) There are no real solution.

Work Step by Step

a) We solve for $x$ in the equation $3 x^2-6 x+\frac{1}{3}=0$ using the quadratic formula with $a=3, b=-6$ and $c=1/3$. $$ \begin{aligned} & x=\frac{6 \pm \sqrt{6^2-4 \cdot 3 \cdot \frac{1}{3}}}{2 \cdot 3} \\ & x=\frac{6 \pm \sqrt{36-4}}{6}=\frac{6 \pm \sqrt{32}}{6} \\ & x=1 \pm \frac{4 \sqrt{2}}{6} \\ & x \approx 0.057 \text { or } x \approx 1.943 . \end{aligned} $$ The solutions are $x \approx 0.057 $ and $x \approx 1.943$. b) We solve for $x$ in the equation $2 x^2-5.1 x+7.2=0$ using the quadratic formula with $a=2, b=-5.1$ and $c=7.2$. $$ x=\frac{5.1 \pm \sqrt{5.1^2-4 \cdot 2 \cdot 7.2}}{2 \cdot 2} =\frac{5.1 \pm \sqrt{-31.59}}{4} $$ There are no real solution.
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