1
NDA Mathematics 14 November 2021
MCQ (Single Correct Answer)
+2.5
-0.83
Change Language
The inverse of a matrix A is given by $\rm \begin{bmatrix} -2 & 1 \\ \frac{3}{2} & -\frac{1}{2} \end{bmatrix}$ What is A equal to?
A
$\rm \begin{bmatrix} 1 & 2 \\ 3 & 4 \end{bmatrix}$
B
$\rm \begin{bmatrix} 1 & -2 \\ -3 & 4 \end{bmatrix}$
C
$\rm \begin{bmatrix} 1 & 2 \\ 3 & -4 \end{bmatrix}$
D
$\rm \begin{bmatrix} -1 & 2 \\ 3 & 4 \end{bmatrix}$
2
NDA Mathematics 14 November 2021
MCQ (Single Correct Answer)
+2.5
-0.83
Change Language
Let $A = \begin{bmatrix} 0 & 2 \\ -2 & 0 \end{bmatrix}$ and (mI + nA)2 = A where m, n are positive real numbers and I is the identify matrix. What is (m + n) equal to?
A
0
B
$\frac{1}{2}$
C
1
D
$\frac{3}{2}$
3
NDA Mathematics 14 November 2021
MCQ (Single Correct Answer)
+2.5
-0.83
Change Language

Consider the following in respect of the matrix $\rm A = \begin{bmatrix} 1 & 1 & 1\\ 1 & 1 & 1\\ 1 & 1 & 1 \end{bmatrix}$

1. Inverse of A does not exist

2. A3 = A

3. 3A = A2

Which of the above are correct?

A
1 and 2 only
B
2 and 3 only
C
1 and 3 only
D
1, 2 and 3
4
NDA Mathematics 18 April 2021
MCQ (Single Correct Answer)
+2.5
-0.83
Change Language
If A and B are two matrices such that AB is of order n × n, then which one of the following is correct?
A
A and B should be square matrices of same order.
B
Either A or B should be a square matrix.
C
Both A and B should be of same order
D
Orders of A and B need not be the same.
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