Trigonometry (11th Edition) Clone

Published by Pearson
ISBN 10: 978-0-13-421743-7
ISBN 13: 978-0-13421-743-7

Chapter 8 - Complex Numbers, Polar Equations, and Parametric Equations - Section 8.1 Complex Numbers - 8.1 Exercises - Page 364: 91

Answer

The solution set of this problem is $$\Big\{3\pm i\sqrt5\Big\}$$

Work Step by Step

$$x^2-6x+14=0$$ The equation is already in standard form, so the quadratic formula can immediately be used. $$x=\frac{-b\pm\sqrt{b^2-4ac}}{2a}$$ As $a=1, b=-6, c=14$ $$x=\frac{-(-6)\pm\sqrt{(-6)^2-4\times1\times14}}{2\times1}$$ $$x=\frac{6\pm\sqrt{36-56}}{2}$$ $$x=\frac{6\pm\sqrt{-20}}{2}$$ Now we rewrite $\sqrt{-20}=i\sqrt20=2i\sqrt5$ $$x=\frac{6\pm 2i\sqrt5}{2}$$ Then we simplify $$x=3\pm i\sqrt5$$ The solution set of this problem is $$\Big\{3\pm i\sqrt5\Big\}$$
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