Algebra 2 Common Core

Published by Prentice Hall
ISBN 10: 0133186024
ISBN 13: 978-0-13318-602-4

Chapter 6 - Radical Functions and Rational Exponents - 6-2 Multiplying and Dividing Radical Expressions - Practice and Problem-Solving Exercises - Page 373: 95

Answer

$\dfrac{3}{5}+\dfrac{1}{5}i$

Work Step by Step

Multiplying the numerator and the denominator by the conjugate of the denominator, the given expression, $ \dfrac{2}{3-i} ,$ is equivalent to \begin{align*}\require {cancel} & \dfrac{2}{3-i}\cdot\dfrac{3+i}{3+i} \\\\&= \dfrac{2(3+i)}{3^2-i^2} &\left( \text{use }(a+b)(a-b)=a^2-b^2 \right) \\\\&= \dfrac{2(3+i)}{9-i^2} \\\\&= \dfrac{2(3)+2(i)}{9-i^2} &\left( \text{use Distributive Property } \right) \\\\&= \dfrac{6+2i}{9-i^2} \\\\&= \dfrac{6+2i}{9-(-1)} &\left( \text{use }i^2=-1 \right) \\\\&= \dfrac{6+2i}{9+1} \\\\&= \dfrac{6+2i}{10} \\\\&= \dfrac{\cancel6^3+\cancel2^1i}{\cancel{10}^5} &\left( \text{divide by }2 \right) \\\\&= \dfrac{3+i}{5} \\\\&= \dfrac{3}{5}+\dfrac{1}{5}i .\end{align*} Hence, in the form $a\pm bi,$ the given expression is equivalent to $ \dfrac{3}{5}+\dfrac{1}{5}i $.
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