Precalculus (6th Edition)

Published by Pearson
ISBN 10: 013421742X
ISBN 13: 978-0-13421-742-0

Chapter 8 - Application of Trigonometry - Chapter 8 Test Prep - Review Exercises - Page 841: 58

Answer

$$ - 128 + 128i$$

Work Step by Step

$$\eqalign{ & {\left( {2 - 2i} \right)^5} \cr & {\text{Write in the polar form}} \cr & r = \sqrt {{{\left( 2 \right)}^2} + {{\left( { - 2} \right)}^2}} = 2\sqrt 2 = \cr & \theta = {\tan ^{ - 1}}\left( {\frac{{ - 2}}{2}} \right) = - {45^ \circ } + {360^ \circ } \cr & \theta = {315^ \circ } \cr & {\left( {2 - 2i} \right)^5} = {\left( {2\sqrt 2 \angle {{315}^ \circ }} \right)^5} \cr & {\text{Solve the power}} \cr & = {\left( {2\sqrt 2 } \right)^5}\angle 5 \cdot {315^ \circ } \cr & = {2^7}\sqrt 2 \angle {1575^ \circ } \cr & = 128\sqrt 2 \angle {135^ \circ } \cr & {\text{Write in the rectangular form}} \cr & = 128\sqrt 2 \left( {\cos {{135}^ \circ } + i\sin {{135}^ \circ }} \right) \cr & = 128\sqrt 2 \left( { - \frac{{\sqrt 2 }}{2} + i\frac{{\sqrt 2 }}{2}} \right) \cr & = - 128 + 128i \cr} $$
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