1
JEE Main 2018 (Online) 15th April Morning Slot
+4
-1
Let $$A$$ be a matrix such that $$A.\left[ {\matrix{ 1 & 2 \cr 0 & 3 \cr } } \right]$$ is a scalar matrix and |3A| = 108.
Then A2 equals :
A
$$\left[ {\matrix{ 4 & { - 32} \cr 0 & {36} \cr } } \right]$$
B
$$\left[ {\matrix{ {36} & 0 \cr { - 32} & 4 \cr } } \right]$$
C
$$\left[ {\matrix{ 4 & 0 \cr { - 32} & {36} \cr } } \right]$$
D
$$\left[ {\matrix{ {36} & { - 32} \cr 0 & 4 \cr } } \right]$$
2
JEE Main 2018 (Online) 15th April Morning Slot
+4
-1
Let S be the set of all real values of k for which the systemof linear equations
x + y + z = 2
2x + y $$-$$ z = 3
3x + 2y + kz = 4
has a unique solution. Then S is :
A
an empty set
B
equal to {0}
C
equal to R
D
equal to R $$-$$ {0}
3
JEE Main 2017 (Online) 9th April Morning Slot
+4
-1
For two 3 × 3 matrices A and B, let A + B = 2BT and 3A + 2B = I3, where BT is the transpose of B and I3 is 3 × 3 identity matrix. Then :
A
5A + 10B = 2I3
B
10A + 5B = 3I3
C
B + 2A = I3
D
3A + 6B = 2I3
4
JEE Main 2017 (Online) 8th April Morning Slot
+4
-1
Let A be any 3 $$\times$$ 3 invertible matrix. Then which one of the following is not always true ?
A
adj (A) = $$\left| \right.$$A$$\left| \right.$$.A$$-$$1
B
adj (adj(A)) = $$\left| \right.$$A$$\left| \right.$$.A
C
adj (adj(A)) = $$\left| \right.$$A$$\left| \right.$$2.(adj(A))$$-$$1
D
adj (adj(A)) = $$\left| \, \right.$$A $$\left| \, \right.$$.(adj(A))$$-$$1
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