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Express the following complex number in the standard form a + ib: (2+๐‘–)32+3โข๐‘–

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Question

Express the following complex number in the standard form a + ib:

\[\frac{(2 + i )^3}{2 + 3i}\]

Sum
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Solution

\[\frac{\left( 2 + i \right)^3}{2 + 3i}\]

\[ = \frac{\left( 4 + i^2 + 4i \right)\left( 2 + i \right)}{2 + 3i} \left( \because i^2 = - 1 \right)\]

\[ = \frac{8 + 2 i^2 + 8i + 4i + i^3 + 4 i^2}{2 + 3i} \]

\[ = \frac{2 + 11i}{2 + 3i} \times \frac{2 - 3i}{2 - 3i}\]

\[ = \frac{4 - 6i + 22i - 33 i^2}{4 - 9 i^2}\]

\[ = \frac{37 + 16i}{4 + 9}\]

\[ = \frac{37}{13} + \frac{16}{13}i\]

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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 1.05 | Page 31

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