1
COMEDK 2022
MCQ (Single Correct Answer)
+1
-0

If for any 2 $$\times$$ 2 square matrix A,

A (adj A) = $$\left[ {\matrix{ 8 & 0 \cr 0 & 8 \cr } } \right]$$, then find the value of det (A).

A
6
B
7
C
8
D
5
2
COMEDK 2022
MCQ (Single Correct Answer)
+1
-0

If $$A = \left[ {\matrix{ a & 0 & 0 \cr 0 & a & 0 \cr 0 & 0 & a \cr } } \right]$$, then $$|A||adj\,A|$$ is equal to

A
$${a^{3n}}$$
B
$${a^{-3n}}$$
C
$${-a^{3n}}$$
D
$${2a^{3n}}$$
3
COMEDK 2022
MCQ (Single Correct Answer)
+1
-0

If $$A = \left[ {\matrix{ {2 - k} & 2 \cr 1 & {3 - k} \cr } } \right]$$ is a singular matrix, then the value of $$5k - {k^2}$$ is

A
0
B
6
C
$$-$$6
D
4
4
COMEDK 2022
MCQ (Single Correct Answer)
+1
-0

If $$\theta$$ be the angle between the vectors $$a = 2\widehat i + 2\widehat j - \widehat k$$ and $$b = 6\widehat i - 3\widehat j + 2\widehat k$$, then

A
$$\cos \theta = {4 \over {21}}$$
B
$$\cos \theta = {3 \over {19}}$$
C
$$\cos \theta = {2 \over {19}}$$
D
$$\cos \theta = {5 \over {21}}$$
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