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3 and 4 .Determinants and Matrices
easy
જો $\left| {\,\begin{array}{*{20}{c}}{6i}&{ - 3i}&1\\4&{3i}&{ - 1}\\{20}&3&i\end{array}\,} \right| = x + iy$, તો . . . .
A
$x = 3,y = 1$
B
$x = 0,y = 0$
C
$x = 0,y = 3$
D
$x = 1,y = 3$
(IIT-1998)
Solution
(b) $\,\left| {\,\begin{array}{*{20}{c}}
{6i}&{ – 3i}&1 \\
4&{3i}&{ – 1} \\
{20}&3&i
\end{array}\,} \right| = x + iy$
$ \Rightarrow $ $6i( – 3 + 3) + 3i(4i + 20) + 1(12 – 60i) = x + iy$
$ \Rightarrow $ $(0+60i-12+12-60i)$ $ \Rightarrow $ $x = 0,\,y = 0$.
Standard 12
Mathematics
