Sample QuestionsDETERMINANTS questions
One sample from each question group in this chapter. Select any group above to see the full set with answer keys.
If $A$ is an invertible matrix of order $2,$ then det $(A–1)$ is equal to:
Answer: B.
View full solution →Choose the correct answer from given four options in each of the Exercise:
The value of $\begin{vmatrix}\text{a}-\text{b}&\text{b}+\text{c}&\text{a}\\\text{b}-\text{a}&\text{c}+\text{a}&\text{b}\\\text{c}-\text{a}&\text{a}+\text{b}&\text{c}\end{vmatrix}$ is:
- A
$a^3 + b^3 + c^3$
- B
$3bc$
- C
$a^3 + b^3 + c^3 - 3abc$
- ✓
Answer: D.
View full solution →Choose the correct answer from given four options in each of the Exercise: If $\text{A}=\begin{vmatrix}2&\lambda&-3\\0&2&5\\1&1&3\end{vmatrix},$ then $A^{-1}$ exists, if:
- A
$\lambda=2$
- B
$\lambda\neq2$
- C
$\lambda\neq-2$
- ✓
$\text{None of these}$
Answer: D.
View full solution →The value of $\begin{vmatrix}5^2&5^3&5^4\\5^3&5^4&5^5\\5^4&5^5&5^6\end{vmatrix}$ is:
- A
$5^2$
- ✓
$0$
- C
$5^{13}$
- D
$5^9$
Answer: B.
View full solution →The value of $\text{(adj } A)$ is equal to
Answer: A.
View full solution →Directions : In the following questions, a statement of assertion $(A)$ is followed by a statement of reason $(R).$ Mark the correct choice as:
Assertion : The value of $x$ for which $\begin{vmatrix}\text{x}&2\\18&\text{x}\end{vmatrix}=\begin{vmatrix}6&2\\18&6\end{vmatrix}$ is $\pm\ 6.$
Reason : The determinant of a matrix $A$ order $2\times 2,$ $\text{A}\begin{bmatrix}\text{a}&\text{b}\\\text{c}&\text{d}\end{bmatrix}$ is $= ab - dc.$
- A
Both $A$ and $R$ are true and $R$ is the correct explanation of $A.$
- B
Both $A$ and $R$ are true but $R$ is not the correct explanation of $A.$
- ✓
$A$ is true but $R$ is false.
- D
$A$ is false but $R$ is true.
Answer: C.
View full solution →Directions : In the following questions, a statement of assertion $(A)$ is followed by a statement of reason $(R).$ Mark the correct choice as :
Assertion : For two matrices $A$ and $B$ of order $3, \mid\text{A}\mid=2\mid\text{B}\mid=-3$ then if $\mid2\text{AB}\mid$ is $-48.$
Reason : For a square matrix $A, \text{A}(\text{adj}\ \text{A})=(\text{adj}\ \text{A})\text{A}=\mid\text{A}\mid.$
- A
Both $A$ and $R$ are true and $R$ is the correct explanation of $A.$
- ✓
Both $A$ and $R$ are true but $R$ is not the correct explanation of $A.$
- C
$A$ is true but $R$ is false.
- D
$A$ is false but $R$ is true.
Answer: B.
View full solution →Directions: In the following questions, a statement of assertion $(A)$ is followed by a statement of reason $(R).$ Mark the correct choice as:
Assertion: The value of $x$ for which $\begin{vmatrix}3&\text{x}\\\text{x}&1\end{vmatrix}=\begin{vmatrix}3&2\\4&1\end{vmatrix}$ is $\pm2\sqrt{2}.$
Reason: The determinant of a matrix $A$ order $2 \times 2, \text{A}\begin{bmatrix}\text{a}&\text{b}\\\text{c}&\text{d}\end{bmatrix}$ is $= ad - bc.$
- ✓
Both $A$ and $R$ are true and $R$ is the correct explanation of $A.$
- B
Both $A$ and $R$ are true but $R$ is not the correct explanation of $A.$
- C
$A$ is true but $R$ is false.
- D
$A$ is false but $R$ is true.
Answer: A.
View full solution →Directions : In the following questions, a statement of assertion $(A) $ is followed by a statement of reason $(R).$ Mark the correct choice as :
Assertion : The points $A(a, b + c), B(b, c +a )$ and $C(c, a + b)$ are collinear.
Reason : Three points $A (x_1, y_1) , B(x_2, y_2)$ and $C(x_3, y_3)$ are collinear if area of a triangle $\text{ABC}$ is zero.
- ✓
Both $A$ and $R$ are true and $R$ is the correct explanation of $A$.
- B
Both $A$ and $R$ are true but $R$ is not the correct explanation of $A.$
- C
$A$ is true but $R$ is false.
- D
$A$ is false but $R$ is true.
Answer: A.
View full solution →Directions : In the following questions, a statement of assertion $(A)$ is followed by a statement of reason $(R).$ Mark the correct choice as :
Assertion : For a matrix $\begin{bmatrix}2&-1\\-3&4\end{bmatrix}, A. \text{adj}$ $\text{A}=\begin{bmatrix}4&0\\0&4\end{bmatrix}.$
Reason : For a square matrix $A, \text{A}(\text{adj}\text{A})=(\text{adj}\text{A})\text{A}=\mid\text{A}\mid.$
- A
Both $A$ and $R$ are true and $R$ is the correct explanation of $A.$
- B
Both $A$ and $R$ are true but $R$ is not the correct explanation of $A.$
- C
$A$ is true but $R$ is false.
- ✓
$A$ is false but $R$ is true.
Answer: D.
View full solution →If $\begin{vmatrix} 3 \text{x}& 7 \$0.3em] -2 & 4\$0.3em] \end{vmatrix} = \begin{vmatrix} 8 & 7 \$0.3em] 6 & 4\$0.3em] \end{vmatrix}, $find the value of x.
View full solution →If $\begin{bmatrix} 3 \text{x}& 7 \$0.3em] -2 & 4\$0.3em] \end{bmatrix} = \begin{bmatrix} 8 & 7 \$0.3em] 6 & 4\$0.3em] \end{bmatrix}, $find the value of x.
View full solution →If $\begin{bmatrix} \text{x - y }& \text{z} \$0.3em] 2\text{x - y }& \text{w} \$0.3em] \end{bmatrix} = \begin{bmatrix} -1& 4 \$0.3em] 0 & 5\$0.3em] \end{bmatrix},$find the value of x + y.
View full solution →$\text{If }x \in \text{N and} \begin{bmatrix} \text{x + 3} & -2 \\ \text{-3x} & \text{2x} \\ \end{bmatrix} = 8, $ then find the value of $x.$
View full solution →What positive value of x makes the following pair of determinants equal? .
$\begin{vmatrix}\text{2x}&3\\5&\text{x} \end{vmatrix}, \begin{vmatrix}\text{16}&3\\5&\text{2} \end{vmatrix}$
View full solution →If $\begin{vmatrix}2\text{x}+5&3\\5\text{x}+2&9\end{vmatrix}=0,$ find x.
View full solution →Find the value of the determinant $\begin{vmatrix}4200&1201\\4205&4203\end{vmatrix}$
View full solution →If $A$ is a square matrix of order $3$ with determinant $4$, then write the value of $|-A|.$
View full solution →Examine the consistency of the system of equations:
2x - y = 5
x + y = 4
View full solution →If $\text{A}=\begin{bmatrix}0&\text{i}\\\text{i}&1\end{bmatrix}$ and $\text{B}=\begin{bmatrix}0&1\\1&0\end{bmatrix},$ find the value of $|\text{A}|+|\text{B}|.$
View full solution →Using the properties of determinants, prove that
$ \begin{vmatrix} \text{a + b} & \text{b + c} & \text{c + a} \\ \text{b + c} & \text{c + a} & \text{a + b} \\ \text{c + a} & \text{a + b} & \text{b + c} \end{vmatrix}=2 \begin{vmatrix} \text{a} & \text{b} & \text{c} \\ \text{b} & \text{c} & \text{a} \\ \text{c} & \text{a} & \text{b} \end{vmatrix}$.
View full solution →If $\text{A}= \begin{bmatrix} 3 & 1 \\ -1 & 2 \\ \end{bmatrix},$ show the $\text{A}^{2}-\text{5A}+\text{7I}=0$. Hence find $A^{-1}$.
View full solution →Using properties of determinants, prove the following:
$\begin{vmatrix} 3a & -a + b & -a + c \\ a - b & 3b & c - b \\ a - c & b - c & 3c \end{vmatrix} = 3(a + b + c) (ab + bc + ca) $
View full solution →If $A = \begin{bmatrix} 2 & -3 & \\ 3 & 4 & \\ \end{bmatrix} $ show that $\text{A^{2} - 6 A + 17 I = 0.}$ Hense find $A^{-1}.$
View full solution →Using properties of determinants, prove the following:$ \begin{vmatrix} a - b -c & 2a & 2a \\ 2b & b- c - a & 2b \\ 2c & 2c & c- a -b \end{vmatrix} = (a + b + c)^{3}$
View full solution →Using properties of determinants, prove that
$\begin{vmatrix} \text{a}^{2} + \text{2a} & \text{2a + 1} & 1 \\ \text{2a + 1} & \text{a + 2} & 1 \\ 3 & 3 & 1 \end{vmatrix} = \text{(a - 1)}^{3}$
View full solution →Using properties of determinants, prove that:
$\begin{vmatrix} \text{1 + a } & \text{1} & \text{1} 0.3em] \text{1} & \text{1 + b} & \text{1} 0.3em]\text{1} & 1 &\text{1 + c} \end{vmatrix}= \text{ abc + bc + ca + ab}$
View full solution →Using properties of determinants, prove that
$\begin{vmatrix} \text{b + c } & \text{c + a} & \text{a + b} 0.3em] \text{q } + \text{r} & \text{r + p} & \text{p + q} 0.3em] \text{y + z} & \text{z + x} &\text{x + y} \end{vmatrix}= \text{2}$
$\begin{vmatrix} \text{a } & \text{b} & \text{c} 0.3em] \text{p} & \text{q} & \text{r} 0.3em] \text{x} & \text{y} &\text{z} \end{vmatrix}$
View full solution →Using properties of determinants, show that $\triangle\text{ABC}$ is isosceles if:
$\begin{vmatrix} 1 & 1 & 1 \\ 1 + \cos\text{A} & 1 + \cos\text{B} & 1 + \cos\text{C} \\ \cos^{2}\text{A} + \cos\text{A} & \cos^{2}\text{B}+\cos\text{B} & \cos^{2}\text{C} + \cos\text{C} \end{vmatrix} = 0 $
View full solution →Using properties of determinants, prove the following: $ \begin{bmatrix} \text{ x}&\text{x + y }&\text{x} + 2\text{y}\\ \text{x} + 2\text{y} & \text{x}& \text{x + y }\\\text{x + y}&\text{x} + 2\text{y}& \text{x} \end{bmatrix} = 9\text{y}^{2}(\text{x} + \text{y}). $
View full solution →If there is a statement involving the natural number n such that:
- The statement is true for $n = 1$
- When the statement is true for $n = k ($where $k$ is some positive integer$),$ then the statement is also true for $n = k + 1.$
Then, the statement is true for all natural numbers n.
Also, if $A$ is a square matrix of order n, then $A^2$ is defined as $AA$. In general, $A^m = AA .... A (m$ times$)$. where m is any positive integer.
Based on the above information, answer the following questions.
- If $\text{A}=\begin{bmatrix}3&-4\\1&-1\end{bmatrix},$ then for any positive integer n,
- $\text{A}^\text{n}=\begin{bmatrix}3\text{n}&-4\text{n}\\\text{n}&-\text{n}\end{bmatrix}$
- $\text{A}^\text{n}=\begin{bmatrix}1+2\text{n}&-4\text{n}\\\text{n}&1-2\text{n}\end{bmatrix}$
- $\text{A}^\text{n}=\begin{bmatrix}3\text{n}&-8\text{n}\\1&-\text{n}\end{bmatrix}$
- $\text{A}^\text{n}=\begin{bmatrix}1+3\text{n}&-4\text{n}\\\text{n}&1-3\text{n}\end{bmatrix}$
- If $\text{A}=\begin{bmatrix}1&2\\0&1\end{bmatrix},$ then $|A^n|$, where $\text{n}\in\text{ N},$ is equal to:
- $2^n$
- $3^n$
- $n$
- $1$
- If $\text{A}=\begin{bmatrix}1&0\\1&1\end{bmatrix}$ and $\text{I}=\begin{bmatrix}1&0\\0&1\end{bmatrix}$ then which of the following holds for all natural numbers $\text{n}\geq1?$
- $A^n= nA - (n - 1)I$
- $A^n = 2^{n-1} A - (n - 1)I$
- $A^n= nA + (n - 1)I$
- $A^n = 2^{n-1} A + (n - 1)I$
- Let $\text{A}=\begin{bmatrix}\text{a}&0&0\\0&\text{a}&0\\0&0&\text{a}\end{bmatrix}$ and $\text{A}^\text{n}=[\text{a}_{\text{ij}}]_{3\times3}$ for some positive integer n, then the cofactor of $a_{13}$ is:
- $a^n$
- $-a^n$
- $2a^n$
- $0$
- If $A$ is a square matrix such that $|A| = 2,$ then for any positive integer n, $|A^n|$ is equal to:
- $0$
- $2n$
- $2^n$
- $n^2$
View full solution →Area of a triangle whose vertices are $(x_1, y_1), (x_2, y_2)$ and $(x_3, y_3)$ is given by the determinant:
$\Delta=\frac{1}{2}\begin{vmatrix}\text{x}_1&\text{y}_1&1\\\text{x}_2&\text{y}_2&1\\\text{x}_3&\text{y}_3&1\end{vmatrix}$
Since, area is a positive quantity, so we always take the absolute value of the determinant $\Delta.$ Also, the area of the triangle formed by three collinear points is zero.
Based on the above information, answer the following questions.
- Find the area of the triangle whose vertices are $(-2, 6), (3, -6) $ and $(1, 5).$
- $30$ sq. units
- $35 $ sq. units
- $40$ sq. units
- $15.5$ sq. units
- If the points $(2, -3), (k, -1)$ and $(0, 4)$ are collinear, then find the value of $4k.$
- $4$
- $\frac{7}{140}$
- $47$
- $\frac{40}{7}$
- If the area of a triangle $ABC,$ with vertices $A(1, 3), B(0, 0)$ and $C(k, 0)$ is 3 sq. units, then a value of $k$ is:
- $2$
- $3$
- $4$
- $5$
- Using determinants, find the equation of the tine joining the points $A(1, 2)$ and $B(3, 6).$
- $y = 2x$
- $x = 3y$
- $y = x$
- $4x - y = 5$
- If $\text{A}\equiv(11,7),\text{B}\equiv(5,5)$ and $\text{C}\equiv(-1,3),$ then:
- $\Delta\text{ABC}$ is scalene triangle.
- $\Delta\text{ABC}$ is equilateral triangle.
- $A, B$ and $C$ are collinear.
- None of these.
View full solution →A company produces three products every day. Their production on certain day is $45$ tons. It is found that the production of third product exceeds the production of first product by $8$ tons while the total production of first and third product is twice the production of second product.

Using the concepts of matrices and determinants, answer the following questions.
- If $x, y$ and $z$ respectively denotes the quantity (in tons) of first, second and third product produced, then which of the following is true?
- $x + y + z = 45$
- $x + 8 = z$
- $x - 2y + z = 0$
- All of these.
- If $\begin{pmatrix}1&1&1\\1&0&-2\\1&-1&1\end{pmatrix}^{-1}=\frac{1}{6}\begin{pmatrix}2&2&2\\3&0&-3\\1&-2&1\end{pmatrix}$ then the inverse of $\begin{pmatrix}1&1&1\\1&0&-1\\1&-2&1\end{pmatrix}$ is:
- $\begin{pmatrix}\frac{1}{3}&\frac{1}{3}&\frac{1}{3}\\\frac{1}{2}&0&\frac{-1}{2}\\\frac{1}{6}&\frac{-1}{3}&\frac{1}{6}\end{pmatrix}$
- $\begin{pmatrix}\frac{1}{2}&0&-\frac{1}{2}\\\frac{1}{3}&\frac{1}{3}&\frac{1}{3}\\\frac{1}{6}&\frac{-1}{3}&\frac{1}{6}\end{pmatrix}$
- $\begin{pmatrix}\frac{1}{3}&\frac{1}{2}&\frac{1}{6}\\\frac{1}{3}&0&\frac{-1}{3}\\\frac{1}{3}&\frac{-1}{2}&\frac{1}{6}\end{pmatrix}$
- None of these.
- $x : y : z$ is equal to:
- $12 : 13 : 20$
- $11 : 15 : 19$
- $15 : 19 : 11$
- $13 : 12 : 20$
- Which of the following is not true?
- $|A| = |A'|$
- $(A')^{-1} = (A^{-1})'$
- $A$ is skew synunetric matrix of odd order, then $|A| = 0$
- $|AB| = |A| + |B|$
- Which of the following is not true in the given determinant of $A,$ where A $=[\text{a}_\text{ij}]_{3\times3}?$
- Order of minor is less than order of the det $(A).$
- Minor of an element can never be equal to cofactor of the same element.
- Value of a determinant is obtained by multiplying elements of a row or column by corresponding cofactors.
- Order of minors and cofactors of same elements of $A$ is same.
View full solution →Let $\text{A}=\begin{bmatrix}1&0\\2&1\end{bmatrix},$ and $U_1, U_2$ are e first and second columns respectively of a $2 \times 2$ matrix $U$. Also, let the column matrices $U_1$ and $U_2$ satisfying $\text{AU}_1=\begin{bmatrix}1\\0\end{bmatrix}$ and $\text{AU}_2=\begin{bmatrix}2\\3\end{bmatrix}.$
Based on the above information, answer the following questions.
- The matrix $U_1 + U_2$ is equal to:
- $\begin{bmatrix}1\\-1\end{bmatrix}$
- $\begin{bmatrix}2\\-2\end{bmatrix}$
- $\begin{bmatrix}3\\-3\end{bmatrix}$
- $\begin{bmatrix}4\\-4\end{bmatrix}$
- The value of $|U|$ is:
- $2$
- $-2$
- $3$
- $-3$
- If $\text{X}=\begin{bmatrix}3&2\end{bmatrix}\text{U}\begin{bmatrix}3\\2\end{bmatrix},$ then the value of |X| =
- $3$
- $-3$
- $-5$
- $5$
- The minor of element at the position $a_{22}$ in $U$ is:
- $1$
- $2$
- $-2$
- $-1$
- If $\text{U}=[\text{a}_\text{ij}]_{2\times2},$ then the value of $a_{11}A_{11}+ a_{12}A_{12},$ where $A_{ij} $ denotes the cofactor of $a_{ij},$ is:
- $1$
- $2$
- $-3$
- $3$
View full solution →Gaurav purchased $5$ pens, $3$ bags and $1$ instrument box and pays $₹ 16$. From the same shop, Dheeraj purchased $2$ pens, $1$ bag and $3$ instrument boxes and pays $₹ 19,$ while Ankur purchased $1$ pen, $2$ bags and $4$ instrument boxes and pays $₹ 25.$

Using the concept of matrices and determinants, answer the following questions.
- The cost of one pen is:
- $₹ 2$
- $₹ 5$
- $₹ 1$
- $₹ 3$
- What is the cost of one pen and one bag?
- $₹ 3$
- $₹ 5$
- $₹ 7$
- $₹ 8$
- What is the cost of one pen and one instrument box?
- $₹ 7$
- $₹ 6$
- $₹ 8$
- $₹ 9$
- Which of the following is correct?
- Determinant is a square matrix.
- Determinant is a number associated to a matrix.
- Determinant is a number associated to a square matrix.
- All of the above.
- From the matrix equation $AB = AC,$ it can be concluded that $B = C$ provided:
- $A$ is singular.
- $A$ is non-singular.
- $A$ is symmetric.
- $A$ is square.
View full solution →Fill in the blanks:
If A is a matrix of order $3 × 3,$ then $(A^2)^{-1}= \_\_\_\_\_\_\_\_.$
View full solution →Fill in the blanks:
If A is a matrix of order 3 × 3, then number of minors in determinant of A are ________.
View full solution →Fill in the blanks:
If $\cos2\theta=0,$ then $\begin{vmatrix}0&\cos\theta&\sin\theta\\\cos\theta&\sin\theta&0\\\sin\theta&0&\cos\theta\end{vmatrix}^2=$ _________.
View full solution →Fill in the blanks:
$\begin{vmatrix}0&\text{xyz}&\text{x}-\text{z}\\\text{y}-\text{x}&0&\text{y}-\text{z}\\\text{z}-\text{x}&\text{z}-\text{y}&0\end{vmatrix}=$ ________.
View full solution →Fill in the blanks:
If A is a matrix of order 3 × 3, then |3A| = _______.
View full solution →State True or False for the statements of the following Exercise:
Let $ \begin{vmatrix}\text{a}&\text{p}&\text{x}\\\text{b}&\text{q}&\text{y}\\\text{c}&\text{r}&\text{z}\end{vmatrix}=16,$ then $\Delta_1=\begin{vmatrix}\text{p}+\text{x}&\text{a}+\text{x}&\text{a}+\text{p}\\\text{q}+\text{y}&\text{b} +\text{y}&\text{b}+\text{q}\\\text{r}+\text{z}&\text{c}+ \text{z}&\text{c}+\text{r}\end{vmatrix}=32.$
View full solution →State True or False for the statements of the following Exercise:
If the determinant $\begin{vmatrix}\text{x}+\text{a}&\text{p}+\text{u}&\text{l}+\text{f}\\\text{y}+\text{b}&\text{q}+\text{v}&\text{m}+\text{g}\\\text{z}+\text{c}&\text{r}+\text{w}&\text{n}+\text{h}\end{vmatrix}$ splits into exactly K determinants of order 3, each element of which contains only one term, then the value of K is 8.
View full solution →State True or False for the statements of the following Exercise:
$\begin{vmatrix}\text{x}+1&\text{x}+2&\text{x}+\text{a}\\\text{x}+2&\text{x}+3&\text{x}+\text{b}\\\text{x}+3&\text{x}+4&\text{x}+\text{c}\end{vmatrix}=0,$ where a, b, c are in A.P.
View full solution →State True or False for the statements of the following Exercise:
The determinant $\begin{vmatrix}\sin\text{A}&\cos\text{A}&\sin\text{A}+\cos\text{B}\\\sin\text{B}&\cos\text{A}&\sin\text{B}+\cos\text{B}\\\sin\text{C}&\cos\text{A}&\sin\text{C}+\cos\text{B}\end{vmatrix}$ is equal to zero.
View full solution →State True or False for the statements of the following Exercise:
$\big(\text{A}^3\big)^{-1}=(\text{A}^{-1})^3,$ where A is square matrx and |A| ≠ 0.
View full solution →