MCQ
If ${\Delta _1} = \left| {\,\begin{array}{*{20}{c}}1&0\\a&b\end{array}\,} \right|$ and ${\Delta _2} = \left| {\begin{array}{*{20}{c}}1&0\\c&d\end{array}} \right|$, then ${\Delta _2}{\Delta _1}$is equal to
  • A
    $ac$
  • $bd$
  • C
    $(b - a)(d - c)$
  • D
    None of these

Answer

Correct option: B.
$bd$
b
(b) ${\Delta _2}{\Delta _1} = \left| {\begin{array}{*{20}{c}}1&0\\c&d\end{array}} \right|\,\,\left| {\,\begin{array}{*{20}{c}}1&0\\a&b\end{array}\,} \right| = \left| {\,\begin{array}{*{20}{c}}1&0\\{c + ad}&{bd}\end{array}\,} \right| = bd$.

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

The minimum value of the sum of real numbers $a^{-5}, a^{-4}, 3 a^{-3}, 1, a^8$ and $a^{10}$ with $a>0$ is
$\int_{\frac{1}{2}}^{2}  \frac{x^2ln x}{(1+x^2)^3}dx$
The slope of the tangent to a curve $C : y = y ( x )$ at any point $[ x , y )$ on it is $\frac{2 e ^{2 x }-6 e ^{- x }+9}{2+9 e ^{-2 x }}$. If $C$ passes through the points $\left(0, \frac{1}{2}+\frac{\pi}{2 \sqrt{2}}\right)$ and $\left(\alpha, \frac{1}{2} e ^{2 \alpha}\right)$ then $e ^{\alpha}$ is equal to.
Let $a, b, c, d$ be in arithmetic progression with common difference $\lambda$. If

$\left|\begin{array}{lll} x+a-c & x+b & x+a \\ x-1 & x+c & x+b \\ x-b+d & x+d & x+c \end{array}\right|=2$

then value of $\lambda^{2}$ is equal to $.....$

If the mirror image of the point $\mathrm{P}(3,4,9)$ in the line $\frac{x-1}{3}=\frac{y+1}{2}=\frac{z-2}{1}$ is $(\alpha, \beta, \gamma)$, then $14(\alpha+\beta+\gamma)$ is :
If a $3-$digit number is randomly chosen. What is the probability that either the number itself or some permutation of the number (which is a $3-$digit number) is divisible by $4$ and $5$ ?
Let $\alpha, \beta$ be roots of $x^2+\sqrt{2} x-8=0$. If $\mathrm{U}_{\mathrm{n}}=\alpha^{\mathrm{n}}+\beta^{\mathrm{n}}$, then $\frac{\mathrm{U}_{10}+\sqrt{2} \mathrm{U}_9}{2 \mathrm{U}_8}$ is equal to ............
If $\int_{\pi /2}^x {\sqrt {3 - 2{{\sin }^2}u} } \,du + \int_0^y {\cos t\,dt} = 0,$ then $\frac{{dy}}{{dx}} = $
If $f(x)$ satisfies the relation $f\left( {\frac{{5x - 3y}}{2}} \right)\, = \,\frac{{5f(x) - 3f(y)}}{2}\,\forall x,y\in R$ $f(0) = 1, f '(0) = 2$ then period of $sin \ (f(x))$ is
Let $y=y(x)$ be the solution of the differential equation $x\left(1-x^{2}\right) \frac{d y}{d x}+\left(3 x^{2} y-y-4 x^{3}\right)=0, x>1$ with $y\,(2)=-2$. Then $y\,(3)$ is equal to