Matrices — Course Quiz | Expresswala Academy

Ten questions on matrix types, operations, transposes and inverses. Pick one answer for each.

10 questions, one mark each. 6 to pass. Suggested time: 20 minutes. Your answers are not recorded.

How many entries does a matrix of order $3 \times 4$ have?

A $3$

B $7$

C $4$

D $12$
Which of these is a scalar matrix?

A $\begin{bmatrix} 5 & 0 \\ 0 & 5 \end{bmatrix}$

B $\begin{bmatrix} 5 & 5 \\ 5 & 5 \end{bmatrix}$

C $\begin{bmatrix} 5 & 0 \\ 0 & 2 \end{bmatrix}$

D $\begin{bmatrix} 0 & 5 \\ 5 & 0 \end{bmatrix}$
If $\begin{bmatrix} x + y & 3 \\ 2 & x - y \end{bmatrix} = \begin{bmatrix} 9 & 3 \\ 2 & 1 \end{bmatrix}$ , then

A $x = 4$ , $y = 5$

B $x = 5$ , $y = -4$

C $x = 5$ , $y = 4$

D $x = 9$ , $y = 1$
If $A = \begin{bmatrix} 1 & 2 \\ 3 & 1 \end{bmatrix}$ , then $A^2$ is

A $\begin{bmatrix} 7 & 6 \\ 4 & 7 \end{bmatrix}$

B $\begin{bmatrix} 7 & 4 \\ 6 & 7 \end{bmatrix}$

C $\begin{bmatrix} 1 & 4 \\ 9 & 1 \end{bmatrix}$

D $\begin{bmatrix} 2 & 4 \\ 6 & 2 \end{bmatrix}$
If $A$ is $3 \times 2$ and $B$ is $2 \times 3$ , the order of $BA$ is

A $BA$ is not defined

B $2 \times 2$

C $2 \times 3$

D $3 \times 3$
The transpose of $\begin{bmatrix} 1 & 2 & 3 \\ 4 & 5 & 6 \end{bmatrix}$ is

A $\begin{bmatrix} 4 & 5 & 6 \\ 1 & 2 & 3 \end{bmatrix}$

B $\begin{bmatrix} 1 & 2 \\ 3 & 4 \\ 5 & 6 \end{bmatrix}$

C $\begin{bmatrix} 1 & 4 \\ 2 & 5 \\ 3 & 6 \end{bmatrix}$

D $\begin{bmatrix} 3 & 6 \\ 2 & 5 \\ 1 & 4 \end{bmatrix}$
Which matrix is skew-symmetric?

A $\begin{bmatrix} 4 & 0 \\ 0 & -4 \end{bmatrix}$

B $\begin{bmatrix} 0 & 4 \\ 4 & 0 \end{bmatrix}$

C $\begin{bmatrix} 1 & 4 \\ -4 & 1 \end{bmatrix}$

D $\begin{bmatrix} 0 & 4 \\ -4 & 0 \end{bmatrix}$
If $A = \begin{bmatrix} 2 & 1 \\ 1 & 2 \end{bmatrix}$ and $A^2 - 4A + kI = O$ , find $k$ .

A $4$

B $5$

C $3$

D $-3$
A student buys $3$ notebooks at ₹ $40$ each and $2$ pens at ₹ $25$ each. The product $\begin{bmatrix} 3 & 2 \end{bmatrix}\begin{bmatrix} 40 \\ 25 \end{bmatrix}$ gives the total cost. What is it?

A ₹ $195$

B ₹ $170$

C ₹ $65$

D ₹ $130$
The inverse of $\begin{bmatrix} 2 & 3 \\ 1 & 2 \end{bmatrix}$ is

A $\begin{bmatrix} 2 & -1 \\ -3 & 2 \end{bmatrix}$

B $\begin{bmatrix} -2 & 3 \\ 1 & -2 \end{bmatrix}$

C $\begin{bmatrix} 2 & 3 \\ 1 & 2 \end{bmatrix}$

D $\begin{bmatrix} 2 & -3 \\ -1 & 2 \end{bmatrix}$

Unanswered questions are marked wrong.

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Matrices — Course Quiz

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