MCQ
For any $2 \times 2$ matrix $ A$, if $A(adj.\,\,A)$= $\left[ {\begin{array}{*{20}{c}}{10}&0\\0&{10}\end{array}} \right]$, then $|A|\, = $
  • A
    $0$
  • $10$
  • C
    $20$
  • D
    $100$

Answer

Correct option: B.
$10$
b
(b) $A(adj\,.\,A) = |A|\,I \Rightarrow \,\left| {\,\begin{array}{*{20}{c}}{10}&0\\0&{10}\end{array}\,} \right| = 10\,.\,\left| {\,\begin{array}{*{20}{c}}1&0\\0&1\end{array}\,} \right|$.

Need a full question paper?

Generate a complete, print-ready paper with questions like this in minutes — across 16+ boards, with answer keys.

Start Generating Free

Similar questions

If $A = \left[ {\begin{array}{*{20}{c}}\alpha &2\\2&\alpha \end{array}} \right]$ and $|{A^3}|$=125, then $\alpha = $
Given $A =$$\left[ {\begin{array}{*{20}{c}}1&3\\2&2\end{array}} \right]$ ; $I =$$\left[ {\begin{array}{*{20}{c}}1&0\\0&1\end{array}} \right]$ . $If A - \lambda I$ is a singular matrix then
Let $f:\left[0, \frac{\pi}{2}\right] \rightarrow[0,1]$ be the function defined by $f(x)=\sin ^2 x$ and let $g:\left[0, \frac{\pi}{2}\right] \rightarrow[0, \infty]$ be the function defined by $g(x)=\sqrt{\frac{\pi x}{2}-x^2}$.

(There are two questions based on $PARAGRAPH "II"$, the question given below is one of them)

($1$) The value of $2 \int^{\frac{\pi}{2}} f(x) g(x) d x-\int^{\frac{\pi}{2}} g(x) d x$ us

($2$) The value of $\frac{16}{\pi^3} \int_0^{\frac{\pi}{2}} f(x) g(x) d x$ is

Give the answer or quetion ($1$) and ($2$) 

Choose the correct answer from the given four options.

If $\text{A}=\frac{1}{\pi}\begin{bmatrix}\sin^{-1}(\text{x}\pi)&\tan^{-1}\Big(\frac{\text{x}}{\pi}\Big)\\\sin^{-1}\Big(\frac{\text{x}}{\pi}\Big)&\cot^{-1}(\pi\text{x})\end{bmatrix}$ and $\text{B}=\frac{1}{\pi}\begin{bmatrix}-\cos^{-1}(\text{x}\pi)&\tan^{-1}\Big(\frac{\text{x}}{\pi}\Big)\\\sin^{-1}\Big(\frac{\text{x}}{\pi}\Big)&\tan^{-1}(\pi\text{x})\end{bmatrix}$ then A - B is:

  1. $\text{I}$

  2. $0$

  3. $2\text{I}$

  4. $\frac{1}{2}\text{I}$

The region formed by the inequalities $2 x+3 y-5 \leq 0,4 x-3 y+2 \leq 0$ and $x \geq 0 \ldots \ldots \ldots$
A bag contains 5 red and 3 blue balls. If 3 balls are drawn at random without replacement, then the probability that exactly two of the three balls were red, the first ball being red, is
  1. $\frac{1}{3}$
  2. $\frac{4}{7}$
  3. $\frac{15}{28}$
  4. $\frac{5}{28}$
Which of the following is incorrect
In Graphical solution the redundant constraint is:
The area of the region bounded by the curve $y=\sin x$ between the ordinates $x=0, x=\frac{\pi}{2}$ and the $x$-axis is
The Cartesian equation of the line passing through the point $(1,-3,2)$ and parallel to the line $\vec{r}=(2+\lambda) \hat{i}+\lambda \hat{j}+(2 \lambda-1) \hat{k}$ is