Linear Algebra for Engineers and Scientists Using Matlab (First Edition)

Published by Pearson
ISBN 10: 0139067280
ISBN 13: 978-0-13906-728-0

Chapter 8 - Section 8.1 - Algebraic Theory - Exercises 8.1 - Page 374: 8

Answer

$5$

Work Step by Step

Note: the standard form of a complex number is $a+bi$ where $i = \sqrt -1$ and $a$ and $b$ are real numbers. Note: $i^{2} = \sqrt -1\sqrt -1 = -1$ Note: $\sqrt x\sqrt y = \sqrt xy$. $(\sqrt 3 + i\sqrt 2)(\sqrt 3 - i\sqrt 2)$ Expand out the complex number: $(\sqrt 3)^{2}-i\sqrt 3\sqrt 2+i\sqrt 2\sqrt 3 -i^{2}(\sqrt 2)^{2}$ As seen in the note above, $i^{2} = -1$, so substitute in $-1$. $(\sqrt 3)^{2}-i\sqrt 3\sqrt 2+i\sqrt 2\sqrt 3 -(-1)(\sqrt 2)^{2}$ Simplify: $(\sqrt 3)^{2}-i\sqrt 3\sqrt 2+i\sqrt 2\sqrt 3 +(\sqrt 2)^{2}$ $3-i\sqrt 3\sqrt 2+i\sqrt 2\sqrt 3 +2$ As seen in the note above, $\sqrt x\sqrt y = \sqrt xy$, so simplify further: $3-i\sqrt 6+i\sqrt 6 +2$ Combine like terms, to express the complex number in standard form: $5$
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