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Evaluate the Following Determinant: ∣ ∣ ∣ a + I B C + I D − C + I D a − I B ∣ ∣ ∣ - Mathematics

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Question

Evaluate the following determinant:

\[\begin{vmatrix}a + ib & c + id \\ - c + id & a - ib\end{vmatrix}\]

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Solution

\[∆ = a^2 - i^2 b^2 - \left( i^2 d^2 - c^2 \right)\]
\[ = a^2 - i^2 b^2 - i^2 d^2 + c^2 \]
\[ = a^2 + c^2 - i^2 \left( b^2 + d^2 \right) \left[ \because i^2 = - 1 \right]\]
\[ = a^2 + c^2 + b^2 + d^2\]

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Chapter 6: Determinants - Exercise 6.1 [Page 10]

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RD Sharma Mathematics [English] Class 12
Chapter 6 Determinants
Exercise 6.1 | Q 2.4 | Page 10

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