1
JEE Main 2021 (Online) 26th February Morning Shift
+4
-1
Let A be a symmetric matrix of order 2 with integer entries. If the sum of the diagonal elements of A2 is 1, then the possible number of such matrices is :
A
6
B
4
C
1
D
12
2
JEE Main 2021 (Online) 26th February Morning Shift
+4
-1
The value of $$\left| {\matrix{ {(a + 1)(a + 2)} & {a + 2} & 1 \cr {(a + 2)(a + 3)} & {a + 3} & 1 \cr {(a + 3)(a + 4)} & {a + 4} & 1 \cr } } \right|$$ is :
A
$$-$$2
B
0
C
(a + 2)(a + 3)(a + 4)
D
(a + 1)(a + 2)(a + 3)
3
JEE Main 2021 (Online) 25th February Evening Shift
+4
-1
Let A be a 3 $$\times$$ 3 matrix with det(A) = 4. Let Ri denote the ith row of A. If a matrix B is obtained by performing the operation R2 $$\to$$ 2R2 + 5R3 on 2A, then det(B) is equal to :
A
64
B
16
C
128
D
80
4
JEE Main 2021 (Online) 25th February Evening Shift
+4
-1
If for the matrix, $$A = \left[ {\matrix{ 1 & { - \alpha } \cr \alpha & \beta \cr } } \right]$$, $$A{A^T} = {I_2}$$, then the value of $${\alpha ^4} + {\beta ^4}$$ is :
A
3
B
2
C
1
D
4
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