21.

$\underset{\mathrm{x}\to 0}{\lim }\mathrm{x}{\left(- 1\right)}^{\left[\frac{1}{\mathrm{x}}\right]}$

• 0

• 1

• - 1

• Does not exist

The equation of circle passing through the points (0, 2) (3, 3) and having its centre on the x-axis is

• x² + y² - 14x - 12 = 0

• 3x² + 3y² - 22x - 4 = 0

• 3x² + 3y² - 14x - 12 = 0

• None of the above

If $\sin \left(\mathrm{\theta }\right) = \frac{1}{2}$ and where, $\mathrm{\theta }$ is an obtuse angle, then $\cot \left(\mathrm{\theta }\right)$ is equal to

• $- \frac{1}{\sqrt{3}}$

• $- \sqrt{3}$

• $\frac{1}{\sqrt{3}}$

• $\sqrt{3}$

RAM (Random Access Memory) in a computer is

• main memory

• secondary memory

• Both of them

• None of the above

If two events A and B are mutually exclusive events, then P(A/B) is equal to

• 0

• 1

• $\frac{\mathrm{P}\left(\mathrm{A} \cap \mathrm{B}\right)}{\mathrm{P}\left(\mathrm{B}\right)}$

• $\frac{\mathrm{P}\left(\mathrm{A} \cap \mathrm{B}\right)}{\mathrm{P}\left(\mathrm{A}\right)}$

The roots of the quadratic equation 2x² + 3x + 1 = 0 are

• rational

• irrational

• imaginary

• None of these

The equation of a circle passing through origin and radius is a, is

• (x - a)² + (y - a)² = a²

• x² + y² = a²

• (x - a)² + y² = a²

• None of the above

Compilerin a computer is

• an application software

• a system software

• a package

• a tool

$\frac{\mathrm{d}}{\mathrm{dx}}{\cot }^{-1}\left(\mathrm{x}\right)$ is equal to

• $\frac{1}{1 + {\mathrm{x}}^2}$

• $\frac{- 1}{1 + {\mathrm{x}}^2}$

• $\frac{1}{\sqrt{1 + {\mathrm{x}}^2}}$

• $\frac{- 1}{\sqrt{1 + {\mathrm{x}}^2}}$

If A = $\left[\begin{array}{ccc}1& 0& 1\\ 0& 1& 1\\ 1& 0& 0\end{array}\right]$, then $\mathrm{A}$ is a

• singular

• non-singular

• symmetric

• unit matrix