Precalculus: Mathematics for Calculus, 7th Edition

Published by Brooks Cole
ISBN 10: 1305071751
ISBN 13: 978-1-30507-175-9

Chapter 1 - Section 1.6 - Complex Numbers - 1.6 Exercises - Page 64: 75

Answer

$z\cdot\overline{z}=25$

Work Step by Step

$z=3-4i$ $;$ $w=5+2i$ $z\cdot\overline{z}$ Multiply the complex number $z$ by its conjugate. To obtain the conjugate, change the sign of its imaginary part: $z\cdot\overline{z}=(3-4i)(3+4i)=3^{2}-(4i)^{2}=9-16i^{2}=...$ Substitute $i^{2}$ by $-1$ and simplify: $...=9-16(-1)=9+16=25$
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