Determinants Questions - JEE

Let A and B be two invertible matrices of order 3 × 3. If det(ABAT) = 8 and det(AB−1) = 8, then det(BA−1BT) is equal to

We have $\displaystyle\sum_{r=1}^{n-1} \Delta_r = \Delta_1 + \Delta_2 + \cdots + \Delta_{n-1}$. Evaluate the sum of determinants and find its value.

If $a, b$ and $c$ are unequal, what is the condition that the value of the determinant, $\Delta = \begin{vmatrix} a & a & a+1 \\ b & b & b+1 \\ c & c & c+1 \end{vmatrix}$ is $0$?

Let $\lambda$ and $\alpha$ be real. Then the number of integral values of $\lambda$ for which the system of linear equations$\lambda x + (\sin\alpha)y + (\cos\alpha)z = 0$$x + (\cos\alpha)y + (\sin\alpha)z = 0$$-x + (\sin\alpha)y - (\cos\alpha)z = 0$has non-trivial solutions is

If $A = \begin{bmatrix} 2 & -3 \\ -4 & 1 \end{bmatrix}$, then $\text{adj}(3A^2 + 12A)$ is equal to

If \[\begin{vmatrix} a & a^2 & 1 + a^3 \\ b & b^2 & 1 + b^3 \\ c & c^2 & 1 + c^3 \end{vmatrix} = 0\] and vectors $(1, a, a^2)$, $(1, b, b^2)$ and $(1, c, c^2)$ are non-coplanar, then the product $abc$ equals:

17. Let $M_n = (a_{ij})$ where $i, j = 1, 2, 3, \ldots, n$. We first find out $a_{11}$ for the $n^{\text{th}}$ matrix, which is the $n^{\text{th}}$ term in the series: $1, 2, 6, 15, \ldots$. The diagonal elements of the $n^{\text{th}}$ matrix form an arithmetic progression with first term $1 + \dfrac{n(n-1)(2n-1)}{6}$ and common difference $n+1$. Find the required sum $M_n$.

The equations $(\lambda - 1)x + (3\lambda + 1)y + 2\lambda z = 0$, $(\lambda - 1)x + (4\lambda - 2)y + (\lambda + 3)z = 0$ and $2x + (3\lambda + 1)y + 3(\lambda - 1)z = 0$ give non-trivial solution for some values of $\lambda$, then the ratio $x : y : z$, when $\lambda$ has smallest of these values is:

If $\Delta = \begin{vmatrix} 1 & 3\cos\phi & 1 \\ \sin\phi & 1 & 3\cos\phi \\ 1 & \sin\phi & 1 \end{vmatrix}$, the maximum value of $\Delta$ is

We have \[\Delta_1 = \begin{vmatrix} x & \sin\theta & \cos\theta \\ -\sin\theta & -x & 1 \\ \cos\theta & 1 & x \end{vmatrix}\] and \[\Delta_2 = \begin{vmatrix} x & \sin 2\theta & \cos 2\theta \\ -\sin 2\theta & -x & 1 \\ \cos 2\theta & 1 & x \end{vmatrix}\] Then $\Delta_1 + \Delta_2$ equals:

Let $x, y, z > 1$ and $A = \begin{pmatrix} 1 & \log_x y & \log_x z \\ \log_y x & 2 & \log_y z \\ \log_z x & \log_z y & 3 \end{pmatrix}$. Then $|\text{adj}(\text{adj}A^2)|$ is equal to

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If a₁b₁c₁, a₂b₂c₂ and a₃b₃c₃ are three digit even natural numbers and $\Delta = \begin{vmatrix} c_1 & a_1 & b_1 \\ c_2 & a_2 & b_2 \\ c_3 & a_3 & b_3 \end{vmatrix}$, then $\Delta$ is

If P is an orthogonal matrix and $Q = PAP^T$ and $x = P^T Q^{1000} P$, then $x^{-1}$ is, where A is involutary matrix

If $f(x) = a + bx + cx^2$ and $\alpha, \beta$ and $\gamma$ are the roots of the equation $x^3 = 1$, then $\begin{vmatrix} a & b & c \\ b & c & a \\ c & a & b \end{vmatrix}$ is equal to

If $\begin{vmatrix}x-4&2x&2x\\2x&x-4&2x\\2x&2x&x-4\end{vmatrix}=(A+Bx)(x-A)^2$, then the ordered pair $(A,B)$ is equal to

If the system of equations $x+2ay+az=0$, $x+3by+bz=0$, $x+4cy+cz=0$ has a non-zero solution, then $a,b,c$

Let $A=[a_{ij}]_{2\times2}$, where $a_{ij}\neq0$ for all $i,j$ and $A^2=I$. Let $a$ be the sum of all diagonal elements of $A$ and $b=|A|$. Then $3a^2+4b^2$ is equal to

If $A + B = \text{BA}$ and $A^2 - B^2 = I$, then the value of the determinant of matrix $A^T + B$ (where $A$ and $B$ are square matrices of order $3 \times 3$)

If $a, b, c, \lambda \in \mathbb{N}$, then the least possible value of $\begin{vmatrix} a^2 + \lambda & ab & ac \\ ba & b^2 + \lambda & bc \\ ca & cb & c^2 + \lambda \end{vmatrix}$ is

Let $f(a,b) = \begin{vmatrix} a & a^2 & 0 \\ 1 & 2a + b & (a+b)^2 \\ 0 & 1 & 2a + 3b \end{vmatrix}$. Which is a factor of $f(a,b)$?

For $x \neq y \neq z$, $\begin{vmatrix} 1+x^3 & x^2 & 1 \\ 1+y^3 & y^2 & 1 \\ 1+z^3 & z^2 & 1 \end{vmatrix} = 0$ if $xyz$ is

Suppose $D = \begin{vmatrix} a_1 & b_1 & c_1 \\ a_2 & b_2 & c_2 \\ a_3 & b_3 & c_3 \end{vmatrix}$ and $D' = \begin{vmatrix} a_1+pb_1 & b_1+qc_1 & c_1+ra_1 \\ a_2+pb_2 & b_2+qc_2 & c_2+ra_2 \\ a_3+pb_3 & b_3+qc_3 & c_3+ra_3 \end{vmatrix}$. Then

If $a, b, c$ are different, then the value of $x$ satisfying $\begin{vmatrix} 0 & x^2-a & x^3-b \\ x^2+a & 0 & x^2+c \\ x^4+b & x-c & 0 \end{vmatrix} = 0$ is

The arbitrary constant on which the value of the determinant $\begin{vmatrix} 1 & a & a \\ \cos(\pi - d)a & \cos(\pi a) & \cos(\pi - d)a \\ \sin(\pi - d)a & \sin(\pi a) & \sin(\pi - d)a \end{vmatrix}$ does not depend, is

The number of distinct real values of $K$ such that the system of equations $x+2y+z=1$, $x+3y+4z=K$, $x+5y+10z=K^2$ has infinitely many solutions is

Solve: \[\begin{vmatrix} x^2-1 & x^2+2x+1 & 2x^2+3x+1 \\ 2x^2+x-1 & 2x^2+5x-3 & 4x^2+4x-3 \\ 6x^2-x-2 & 6x^2-7x+2 & 12x^2-5x-2 \end{vmatrix} = 0\]

Let A be a matrix of order 3 $\times$ 3 and |A| = 5. If |2 adj(3 A adj(2 A))| = 2$\alpha$$\cdot$3$\beta$$\gamma$$\cdot$5$\alpha$,$\beta$,$\gamma$$\ in $N then$\alpha$+$\beta$+$\gamma$is equal to

Find the value of the determinant $\begin{vmatrix} 1 & 1 & 1 & 1 \\ 1 & 2 & 3 & 4 \\ 1 & 3 & 6 & 10 \\ 1 & 4 & 10 & 20 \end{vmatrix}$

If $A$ is matrix of order 3 such that $|A|=5$ and $B=\text{adj}\,A$, then the value of $\left\||A^{-1}|(AB)^T\right\|$ is equal to

If $M$ is a square matrix of order 3 such that $|M|=2$, then $\left|\text{adj}\!\left(\dfrac{M}{2}\right)\right|$ equals

For Problems 7 and 8Consider an arbitrary $3 \times 3$ non-singular matrix $A = [a_{ij}]$. A matrix $B = [b_{ij}]$ is formed such that $b_{ij}$ is the sum of all the elements except $a_{ij}$ in the $i$th row of $A$.The value of $|B|$ is equal to

For Problems 12 and 13Let for $A = \begin{bmatrix} 1 & 0 & 0 \\ 2 & 1 & 0 \\ 3 & 2 & 1 \end{bmatrix}$, there be three row matrices $R_1, R_2$ and $R_3$, satisfying the relations, $R_1 A = [1\ 0\ 0]$, $R_2 A = [2\ 3\ 0]$ and $R_3 A = [2\ 3\ 1]$. If $B$ is square matrix of order 3 with rows $R_1, R_2$ and $R_3$ in order, thenThe value of det.(B) is

If $A$ is a square matrix of order 3 such that $\det(A)=3$ and $\det(adj(-4\cdot adj(-3\cdot adj(3\cdot adj((2A)^{-1})))))=2^m3^n$. Then $m+2n$ is equal to

l, m and n are the pth, qth and rth terms of an GP and all positive, then $\begin{vmatrix} \log l & p & 1 \\ \log m & q & 1 \\ \log n & r & 1 \end{vmatrix}$ equals

If A is an 3 × 3 non-singular matrix such that $AA' = A'A$ and $B = A^{-1}A'$, then $BB'$ equals:

Let $B^2 = I$ and $AB = \begin{bmatrix} p & x & a \\ b & q & y \\ z & c & r \end{bmatrix}$. Given that $\text{tr}(AB + AB^3 + \cdots + AB^{19}) = 210$, find the number of ordered triplets $(p, q, r)$ where $p, q, r \in \mathbb{N}$ and $p + q + r = 21$.

For Problems 4–6If $A$ and $B$ are two square matrices of order $3 \times 3$ which satisfy $AB = A$ and $BA = B$, then$(A + B)^7$ is equal to

If the system of equations $\alpha x + y + z = \alpha - 1$, $x + \alpha y + z = \alpha - 1$, $x + y + \alpha z = \alpha - 1$ has non-zero solutions, then the condition on $\alpha$ is:

If $\alpha, \beta, \gamma$ are the roots of $px^3 + qx^2 + r = 0$, then the value of the determinant $\begin{vmatrix} \alpha\beta & \beta\gamma & \gamma\alpha \\ \beta\gamma & \gamma\alpha & \alpha\beta \\ \gamma\alpha & \alpha\beta & \beta\gamma \end{vmatrix}$ is

The value of determinant $\begin{vmatrix} \log_a\left(\frac{x}{y}\right) & \log_a\left(\frac{y}{z}\right) & \log_a\left(\frac{z}{x}\right) \\ \log_{a^2}\left(\frac{y}{z}\right) & \log_{a^2}\left(\frac{z}{x}\right) & \log_{a^2}\left(\frac{x}{y}\right) \\ \log_{a^3}\left(\frac{z}{x}\right) & \log_{a^3}\left(\frac{x}{y}\right) & \log_{a^3}\left(\frac{y}{z}\right) \end{vmatrix}$ is

If $A = \begin{bmatrix} \cos\alpha & -\sin\alpha \\ \sin\alpha & \cos\alpha \end{bmatrix}$ and $A + A^T = I$, find the value of $\alpha$.

If $A$ is a non-diagonal involutory matrix, then

Let $M$ denote the matrix $\begin{pmatrix} 0 & i \\ i & 0 \end{pmatrix}$, where $i^2 = -1$, and let $I$ denote the identity matrix $\begin{pmatrix} 1 & 0 \\ 0 & 1 \end{pmatrix}$. Then the matrix $I + M + M^2 + M^3 + M^4 + \ldots + M^{2010}$ is equal to:

Let $A$ be a non-singular idempotent matrix of order $2025\times2025$. Consider statements: (i) Trace of $A$ = 2025, (ii) $A$ has to be a scalar matrix, (iii) Trace of adjoint of $A^2$ = 2025. Which are true?

Matrix $A$ such that $A^2 = 2A - I$, where $I$ is the identity matrix, then for $n \geq 2$, $A^n$ is equal to

\[f(x) = \begin{vmatrix} \cos x & x & 1 \\ 2\sin x & x^2 & 2x \\ \tan x & x & 1 \end{vmatrix}\] Then find the value of $\displaystyle\lim_{x \to 0} \frac{f(x)}{x}$.

For the system of equations $(k+2)x + 10y = k$ $kx + (k+3)y = k - 1$ to have no solution, the number of values of $ k $ is:

If $A$ is a $3 \times 3$ non-singular matrix such that $AA' = A'A$ and $B = A^{-1}A'$, then $BB'$ equals

If $A, B, C$ are angles of a triangle, then the value of $\begin{vmatrix} e^{2iA} & e^{-iC} & e^{-iB} \\ e^{-iC} & e^{2iB} & e^{-iA} \\ e^{-iB} & e^{-iA} & e^{2iC} \end{vmatrix}$ is

Determinants Questions (2072)