Intermediate Algebra for College Students (7th Edition)

Published by Pearson
ISBN 10: 0-13417-894-7
ISBN 13: 978-0-13417-894-3

Chapter 7 - Section 7.7 - Complex Numbers - Exercise Set - Page 572: 143

Answer

$\frac{8}{5}+\frac{16}{5}i$.

Work Step by Step

$=\frac{8}{1+\frac{2}{i}}$ $=\frac{8}{\frac{i}{i}+\frac{2}{i}}$ Add numerators because denominators are the same. $=\frac{8}{\frac{i+2}{i}}$ Invert the divisor and multiply. $=\frac{8i}{2+i}$ The conjugate of the denominator is $2-i$. Multiply the numerator and the denominator by $2-i$. $=\frac{8i}{2+i}\cdot \frac{2-i}{2-i}$ Use the special formula $(A+B)^2=A^2+2AB+B^2$ Use $i^2=-1$. $=\frac{16i+8}{4+1}$ Simplify. $=\frac{16i+8}{5}$ Rewrite as $a+ib$. $=\frac{8}{5}+\frac{16}{5}i$.
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