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If Z = 1 ( 2 + 3 I ) 2 , than | Z | = - Mathematics

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प्रश्न

\[\text { If } z = \frac{1}{(2 + 3i )^2}, \text { than } \left| z \right| =\]

विकल्प

  • \[\frac{1}{13}\]

  • \[\frac{1}{5}\]

  • \[\frac{1}{12}\]

  • none of these

MCQ
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उत्तर

\[\frac{1}{13}\]

\[\text { Let } z = \frac{1}{\left( 2 + 3i \right)^2}\]

\[ \Rightarrow z = \frac{1}{4 + 9 i^2 + 12i} \]

\[ \Rightarrow z = \frac{1}{4 - 9 + 12i} \]

\[ \Rightarrow z = \frac{1}{- 5 + 12i}\]

\[\Rightarrow z=\frac{1}{- 5 + 12i}\times\frac{- 5 - 12i}{- 5 - 12i}\]

\[\Rightarrow z=\frac{- 5 - 12i}{25 + 144}\]

\[ \Rightarrow z=\frac{- 5}{169}-\frac{12i}{169}\]

\[\Rightarrow\left| z \right|=\sqrt{\frac{25}{{169}^2} + \frac{144}{{169}^2}}\]

\[\Rightarrow \left| z \right|=\frac{1}{\sqrt{169}}\]

\[\Rightarrow \left| z \right| = \frac{1}{13}\]

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अध्याय 13: Complex Numbers - Exercise 13.6 [पृष्ठ ६५]

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आरडी शर्मा Mathematics [English] Class 11
अध्याय 13 Complex Numbers
Exercise 13.6 | Q 21 | पृष्ठ ६५

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