Elementary Geometry for College Students (6th Edition)

Published by Brooks Cole
ISBN 10: 9781285195698
ISBN 13: 978-1-28519-569-8

Appendix A - A.5 - The Quadratic Formula and Square Root Properties - Exercises - Page 555: 20


$x = -4~~$ or $~~x=-3$

Work Step by Step

A quadratic equation can be written in this form: $ax^2 + bx+c = 0$ where $a,b,$ and $c$ are real numbers and $a \neq 0$ We can determine the values of $a, b,$ and $c$: $x^2+7x+12 = 0$ $a = 1$ $b = 7$ $c=12$ We can use the quadratic formula to find the solutions of the equation: $x = \frac{-b \pm \sqrt{b^2-4ac}}{2a}$ $x = \frac{-(7) \pm \sqrt{(7)^2-(4)(1)(12)}}{(2)(1)}$ $x = \frac{-7 \pm \sqrt{49-48}}{2}$ $x = \frac{-7 \pm \sqrt{1}}{2}$ $x = \frac{-7 \pm 1}{2}$ $x = \frac{-7 - 1}{2}~~$ or $~~x = \frac{-7 + 1}{2}$ $x = -4~~$ or $~~x=-3$
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