Precalculus: Mathematics for Calculus, 7th Edition

Published by Brooks Cole
ISBN 10: 1305071751
ISBN 13: 978-1-30507-175-9

Chapter 1 - Section 1.5 - Equations - 1.5 Exercises: 65

Answer

$x_1 = 5;$ $x_2 = -3$

Work Step by Step

$Find$ $all$ $real$ $solutions$ $of$ $the$ $quadratic$ $equation:$ $x^2-2x-15$ Use the Quadratic Equation Formula: $x = \frac{-b \pm \sqrt {b^2-4ac}}{2a}$ $1x^2-2x-15$ $a = 1, b = -2, c = -15$ $x = \frac{-(-2) \pm \sqrt {(-2)^2- 4(1 \times -15)}}{2(1)}$ $x = \frac{2 \pm \sqrt {4 + 60}}{2}$ $x = \frac{2 \pm \sqrt {64}}{2}$ $x_1 = \frac{2 + 8 }{2}, x_2 = \frac{2-8}{2}$ $x_1 = \frac{10}{2}, x_2 = \frac{-6}{2}$ $x_1 = 5;$ $x_2 = -3$
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