College Algebra (6th Edition)

Published by Pearson
ISBN 10: 0-32178-228-3
ISBN 13: 978-0-32178-228-1

Chapter 1 - Equations and Inequalities - Exercise Set 1.4 - Page 143: 77

Answer

$\dfrac{8}{1+\dfrac{2}{i}}=\dfrac{8}{5}+\dfrac{16}{5}i$

Work Step by Step

$\dfrac{8}{1+\dfrac{2}{i}}$ Evaluate the sum on the denominator: $\dfrac{8}{1+\dfrac{2}{i}}=\dfrac{8}{\dfrac{2+i}{i}}=...$ Evaluate the division: $...=\dfrac{8i}{2+i}=...$ Multiply the numerator and in the denominator of the fraction by the complex conjugate of the denominator: $...=\dfrac{8i}{2+i}\cdot\dfrac{2-i}{2-i}=\dfrac{8i(2-i)}{2^{2}-i^{2}}=\dfrac{16i-8i^{2}}{4-i^{2}}=...$ Substitute $i^{2}$ by $-1$ and simplify: $...=\dfrac{16i-8(-1)}{4-(-1)}=\dfrac{8+16i}{4+1}=\dfrac{8+16i}{5}=\dfrac{8}{5}+\dfrac{16}{5}i$
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