If $A=\begin{bmatrix} 1 &0 &0 \\ 0& 1 &1 \\ 0&-2 & 4 \end{bmatrix}$ and $6A^{–1} = A^{2} + cA + dI$, where $A^{–1}$ is A- inverse, I is the identify matrix, then (c, d)
is
Consider the matrix $$B=\begin{pmatrix}{-1} & {-1} & {2} \\ {0} & {-1} & {-1} \\ {0} & {0} & {-1}\end{pmatrix}$$. The sum of all the entries of the matrix $B^{19}$ is
The value of ‘a’ for which the system of equations
$a^3 x + (a+1)^3 y + (a+2)^3 z = 0$
$ax + (a+1) y + (a+2) z = 0$
$x + y + z = 0$
has a non–zero solution, is
For non-zero solution, determinant must be zero.
Matrix:
$\begin{vmatrix}
a^3 & (a+1)^3 & (a+2)^3 \
a & a+1 & a+2 \
1 & 1 & 1
\end{vmatrix} = 0$
Factor out structure:
This determinant becomes zero when columns become linearly dependent → when $a=-1$ or $a=0$ or $a=1$.
Checking each value in equations:
• $a = -1$ → valid
• $a = 0$ → equations collapse but still allow nonzero solution
• $a = 1$ → also gives dependence
But only one of these matches the options where system definitely has non-zero solution.
Correct value = $-1$
Let A and B be two square matrices of same order satisfying $A^2+5A+5I =0$ and $B^2+3B+I=0$ repectively. Where I is the identity matrix. Then the inverse of the matrix $C= BA+2B+2A+4I$ is
If x, y and z are three cube roots of 27, then the determinant of the matrix $\begin{bmatrix}{x} & {y} & {z} \\ {y} & {z} & {x} \\ {z} & {x} & {y}\end{bmatrix}$ is
If $x, y, z$ are three cube roots of $27$, then the determinant of the matrix
\[
\begin{pmatrix}
x & y & z\\[4pt]
y & z & x\\[4pt]
z & x & y
\end{pmatrix}
\]
is:
The cube roots of $27 = 3^3$ are:
\[
x = 3,\qquad y = 3\omega,\qquad z = 3\omega^2,
\]
where $\omega$ is a cube root of unity satisfying
\[
\omega^3 = 1,\qquad 1+\omega+\omega^2 = 0.
\]
For a circulant matrix, the determinant is:
\[
(x+y+z)(x+\omega y+\omega^2 z)(x+\omega^2 y+\omega z).
\]
Now compute the first factor:
\[
x+y+z = 3(1+\omega+\omega^2) = 3\cdot 0 = 0.
\]
Therefore,
\[
\det = 0.
\]
If $A=\begin{bmatrix} a &b &c \\ b & c & a\\ c& a &b \end{bmatrix}$ , where $a, b, c$ are real positive numbers such that $abc = 1$ and $A^{T}A=I$ then
the equation that not holds true among the following is
If $f(x)=\left\{\begin{matrix} \frac{sin[x]}{[x]} &, [x]\ne0 \\ 0 &, [x]=0 \end{matrix}\right.$ , where [x] is the largest integer but not larger than x, then $\lim_{x\to0}f(x)$ is
The matrix $A$ has $x$ rows and $(x+5)$ columns and the matrix $B$ has $y$ rows and $(11-y)$ columns. If both the matrices $AB$ and $BA$ exist, then value of $x$ and $y$ are
A matrix $M_r$ is defined as $M_r=\begin{bmatrix} r &r-1 \\ r-1&r \end{bmatrix} , r \in N$ then the value of $det(M_1) + det(M_2) +...+ det(M_{2015})$ is