| cc a+i b & c+i d -c+i d & a-i b |=? - Vidyadip

MCQ

$\left|\begin{array}{cc}a+i b & c+i d \\ -c+i d & a-i b\end{array}\right|=?$

A
$\left(a^2-b^2-c^2-d^2\right)$
B
$\left(a^2+b^2+c^2-d^2\right)$
C
$\left(a^2-b^2+c^2-d^2\right)$
✓
$\left(a^2+b^2+c^2+d^2\right)$

✓

Answer

Correct option: D.

$\left(a^2+b^2+c^2+d^2\right)$

(d) $\left(a^2+b^2+c^2+d^2\right)$
Explanation: $\Delta=( a + ib )( a - ib )+( c - id )( c + id )=\left( a ^2+ b ^2+ c ^2+ d ^2\right)$

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