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Express the Following Complex Number in the Standard Form a + I B: 1 ( 2 + I ) 2

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Question

Express the following complex number in the standard form a + i b:

\[\frac{1}{(2 + i )^2}\]

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Solution

\[\frac{1}{\left( 2 + i \right)^2}\]

\[ = \frac{1}{4 + i^2 + 4i} \left( \because i^2 = - 1 \right)\]

\[ = \frac{1}{3 + 4i}\]

\[ = \frac{1}{3 + 4i} \times \frac{3 - 4i}{3 - 4i}\]

\[ = \frac{3 - 4i}{9 - 16 i^2}\]

\[ = \frac{3 - 4i}{9 + 16}\]

\[ = \frac{3}{25} - \frac{4}{25}i\]

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Chapter 13: Complex Numbers - Exercise 13.2 [Page 31]

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R.D. Sharma Mathematics [English] Class 11
Chapter 13 Complex Numbers
Exercise 13.2 | Q 1.03 | Page 31

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