Intermediate Algebra: Connecting Concepts through Application

Published by Brooks Cole
ISBN 10: 0-53449-636-9
ISBN 13: 978-0-53449-636-4

Chapter 4 - Quadratic Functions - 4.6 Solving Quadratic Equations by Using the Quadratic Formula - 4.6 Exercises - Page 372: 3

Answer

$\color{blue}{\left\{2, 5\right\}}$

Work Step by Step

The solutions of the quadratic equation $ax^2+bx+c=0$ can be found using the quadratic formula: $$x=\dfrac{-b\pm\sqrt{b^2-4ac}}{2a}$$ The given quadratic equation has $a=1, b=-7, \text{ and } c= 10$. Substitute these values into the quadratic formula to obtain: \begin{align*} x&=\frac{-(-7)\pm\sqrt{(-7)^2-4(1)(10)}}{2(1)}\\\\ x&=\frac{7\pm \sqrt{49-40}}{2}\\\\ x&=\frac{7\pm \sqrt{9}}{2}\\\\ x&=\frac{7\pm 3}{2}\\\\ \end{align*} Thus, $x_1=\dfrac{7-3}{2}=\dfrac{4}{2}=2\\\\$ $x_2=\dfrac{7+3}{2}=\dfrac{10}{2}=5$ Therefore, the solution set is $\color{blue}{\left\{2, 5\right\}}$.
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