\[{\text{In }}{\mathbb{R}^2},{\text{ the set }}\left\{ {\left( {x,y} \right):\left( {{x^2} + {y^2} \leqslant a} \right)\,\, \vee \,\left( {{x^2} + {y^2} \geqslant b} \right),a < b} \right\}\,{\text{is a region}}{\text{.}}\]

• A) False
• B) True
• C)
• D)

The limit of the function $f(x) = \frac{{xy}}{{{x^2} + {y^2}}}$ by letting $\left( {x,{\rm{ }}y} \right)$approach $\left( {0,{\rm{ }}0} \right)$along the line $y{\rm{ }} = {\rm{ }}x$ is ________.

• A) $$- \frac{1}{2}$$
• B) $$\frac{1}{2}$$
• C) Finite
• D) Undefined

${\text{If }}\phi \ne S \subseteq {\mathbb{R}^n},{\text{ then the set }}S{\text{ is bounded if - - - - - - - }}{\text{.}}$

• A) ${\text{sup}}\left\{ {\left| {X - Y} \right|:X,Y \in S} \right\} = \infty $
• B) ${\text{sup}}\left\{ {\left| {X - Y} \right|:X,Y \in S} \right\} < \infty \,$
• C) $\inf \left\{ {\left| {X - Y} \right|:X,Y \in S} \right\} = \infty $
• D) $\inf \left\{ {\left| {X - Y} \right|:X,Y \in S} \right\} < \infty $

${\text{A compact set in }}{\mathbb{R}^n}{\text{ is - - - - - - - - - - }}{\text{.}}$

• A) ${\text{closed and bounded}}$
• B) ${\text{closed and unbounded}}$
• C) ${\text{open and unbounded}}$
• D) ${\text{open and bounded}}$

${\text{An open disc: }}\left\{ {\left( {x,y} \right):{x^2} + {y^2} < 1} \right\}{\text{ in }}{\mathbb{R}^2}{\text{ is - - - - - - }}{\text{.}}$

• A) ${\text{connected polygonally}}$
• B) ${\text{diconnected}}$
• C) ${\text{disconnected polygonally}}$
• D) ${\text{none of these}}{\text{.}}$

$$\begin{gathered} {\text{In }}{\mathbb{R}^n}{\text{, if }}{S_1},{S_2},{S_3} \ldots \,\,{\text{are non - empty closed subsets such that }}{S_1} \supset {S_2} \supset \cdots \; \supset {S_r} \supset \cdots {\text{ and }} \hfill \\ {\text{sup}}\left\{ {\left| {{X_r} - {Y_r}} \right|:{X_r},{Y_r} \in {S_r},r \geqslant 1} \right\} \to 0{\text{ as }}r \to \infty {\text{,then the order of set }}\mathop \cap \limits_{r = 1}^\infty {S_r} = - - - . \hfill \\\ \end{gathered}$$

• A) $$\operatorname{infinite}$$
• B) $${\text{one}}$$
• C) $${\text{finite but more than one}}$$
• D) $${\text{zero}}$$

$\begin{gathered} {\text{In }}{\mathbb{R}^3},{\text{ the lines }}{{\text{L}}_{\text{1}}}:X = \left( {2, - 1,5} \right) + \alpha \left( {2, - 1,3} \right){\text{ and }}{{\text{L}}_2}:X = \left( {2, - 1,5} \right) + \beta \left( { - 5,\frac{5}{2}, - \frac{{15}}{2}} \right){\text{ are traversed}} \hfill \\ {\text{in - - - - - - - - - directions, where }} - \infty < \alpha ,\beta < \infty . \hfill \\\ \end{gathered}$

• A) ${\text{perpendicular}}$
• B) ${\text{same}}$
• C) ${\text{opposite}}$
• D) ${\text{oblique}}$

${\text{The set }}\left\{ {\left( {x,y} \right): - n < x,y < n,\left( {x,y} \right) \ne \left( {0,0} \right),n \in \mathbb{N}} \right\}{\text{ is - - - - - - in }}{\mathbb{R}^{\text{2}}}.$

• A) open
• B) neither open nor closed
• C) closed
• D) both open or closed

A set A ⊂ R of real numbers is ------------------if there exists a real number m ∈ R, such that
x ≥ m for every x ∈ A.

• A) None of these
• B) bounded above
• C) uniformly continuous
• D) bounded below

$$\begin{gathered} {\text{If a function }}f{\text{ is }}continuous{\text{ on a }}compact{\text{ set }}S{\text{ in }}{\mathbb{R}^n}{\text{, and }}\alpha = \mathop {\inf }\limits_{X \in S} f\left( X \right),\,\beta = \mathop {\sup }\limits_{X \in S} f\left( X \right)\,, \hfill \\ {\text{then }}f\left( {{X_1}} \right){\text{ = }}\alpha {\text{ and }}f\left( {{X_2}} \right){\text{ = }}\beta \, - - - - - {X_1}{\text{ and }}{X_2}{\text{ in }}S. \hfill \\\ \end{gathered}$$

• A) for all
• B) for some
• C)
• D)

$${\text{If }}f\left( t \right) = \sqrt t {\text{, }}g\left( {x,y} \right) = 1 - {x^2} - 2{y^2}{\text{, then the domain of }}f \circ g = {\text{ - - - - - - }}{\text{.}}$$

• A) $$\mathbb{R}$$
• B) $$\left\{ {\left( {x,y} \right):{x^2} - 2{y^2} \leqslant 1} \right\}$$
• C) $${\mathbb{R}^2}$$
• D) $$\left\{ {\left( {x,y} \right):{x^2} - 2{y^2} \geqslant 1} \right\}$$

Identify the true statement(s)

• A) For a functions of $n$ variables $$f({\mathbf{X}})$$ the partial derivative with respect to variable $${x_2}$$ is $$\frac{{\partial f({\mathbf{X}})}}{{\partial {{\mathbf{E}}_2}}}$$
• B) A function of several variables is continuous then it is differentiable.
• C) A function of several variables is differentiable if all of its partial derivatives exists.
• D) $$L(x) = 2x - 3{x^2}$$ is a linear function.

Which statement(s) is(are) true about the function $$f(x,y) = \frac{{{x^2} + {y^2}}}{{x - y}}$$,

• A) $$f$$ is differentiable every where except at the points where $$y = x$$
• B) $${f_y}(x,y),{\text{ }}{f_x}(x,y)$$ are continuous everywhere.
• C) $${f_y}(x,y) = \frac{y}{{x - y}} + \frac{{{x^2} + {y^2}}}{{{{(x - y)}^2}}}.$$
• D) $${f_x}(x,y) = \frac{{2x}}{{x - y}} - \frac{{{x^2} + {y^2}}}{{{{(x + y)}^2}}}$$

If f is continuous on a compact set S in ${\mathbb{R}^n}$, then f is __________ on S.

• A) Bounded
• B) All of these
• C) Superemum
• D) Differentiable

$$\begin{gathered} {\text{If }}g\left( {x,y} \right) = \sqrt {1 - {x^2} - 2{y^2}} ,{\text{ }}\,f\left( t \right){\text{ = }}\left\{ \begin{gathered} \frac{{\sin t}}{t},\,t \ne 0\,\, \hfill \\ 1,\,\,\,\,\,\,\,\,\,t = 0 \hfill \\\ \end{gathered} \right., \hfill \\ {\text{then domain of }}f \circ g = - - - - - . \hfill \\\ \end{gathered}$$

• A) $${\mathbb{R}^2}$$
• B) $$\left\{ {\left( {x,y} \right):{x^2} - 2{y^2} \geqslant 1} \right\}$$
• C) $$\left\{ {\left( {x,y} \right):{x^2} - 2{y^2} \leqslant 1} \right\}$$
• D) $$\mathbb{R}$$

$$\begin{gathered} {\text{The domain of the real valued function }}f:{\mathbb{R}^2} \to \mathbb{R}{\text{ defined and given by;}} \hfill \\\ f\left( X \right){\text{ = }}\frac{{\sin \sqrt {1 - {x^2} - 2{y^2}} }}{{\sqrt {1 - {x^2} - 2{y^2}} }}{\text{ is - - - - - of the region}}\,\,{\text{by the ellipse }}{x^2} + 2{y^2} = 1{\text{ }}{\text{.}} \hfill \\\\ \end{gathered}$$

• A) $${\text{exterior}}$$
• B) $${\text{interior and boundary}}$$
• C) $${\text{exterior}}\,\,{\text{and}}\,\,{\text{boundary}}$$
• D) $${\text{interior}}$$

$$\mathop {\lim }\limits_{\left( {x,y} \right) \to \left( {a,b} \right)} \frac{{\sin \sqrt {1 - {x^2} - 2{y^2}} }}{{\sqrt {1 - {x^2} - 2{y^2}} }} = 1,{\text{ if - - - - - - }}{\text{.}}$$

• A) $$\left( {{a^2} + 2{b^2}} \right)\mathop > \limits_ < 1$$
• B) $$\left( {{a^2} + 2{b^2}} \right) > 1$$
• C) $$\left( {{a^2} + 2{b^2}} \right) < 1$$
• D) $$\left( {{a^2} + 2{b^2}} \right) = 1$$

$$\begin{gathered} {\text{In }}{\mathbb{R}^2},{\text{ for the function }}g\left( {x,y} \right){\text{ = }}\left\{ \begin{gathered} \frac{{xy}}{{{x^2} + {y^2}}},\,\,\,\,\left( {x,y} \right) \ne \left( {0,0} \right) \hfill \\ 0,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\left( {x,y} \right) = \left( {0,0} \right) \hfill \\\ \end{gathered} \right., \hfill \\ \frac{{\partial g}}{{\partial x}}\left( {0,0} \right) = \frac{{\partial g}}{{\partial y}}\left( {0,0} \right),\,{\text{and }}g\left( {x,y} \right){\text{ is - - - - - - - at }}\left( {0,0} \right). \hfill \\\ \end{gathered}$$

• A) Continuous
• B) Discontinuous
• C)
• D)

$${\text{In }}{\mathbb{R}^2},{\text{ for the function }}f\left( {x,y} \right) = {x^2} + 2xy,\,\,{\text{the }}\left( {{d_{\left( {2,1} \right)}}f} \right)\left( {X - \left( {2,1} \right)} \right) = - - - - .$$

• A) $$2\left( {x - 2} \right) + 6\left( {y - 1} \right)$$
• B) $$6\left( {x - 2} \right) + 4\left( {y - 1} \right)\,$$
• C) $$4\left( {x - 2} \right) + 6\left( {y - 1} \right)$$
• D) $$6\left( {x - 2} \right) + 2\left( {y - 1} \right)$$

Identify the false statement(s)

• A) None of these
• B) The partial derivative is a special case of directional derivative.
• C) For a functions of n variables $$f({\mathbf{X}})$$ the partial derivative with respect to variable $${x_2}$$ is $$\frac{{\partial f({\mathbf{X}})}}{{\partial {{\mathbf{E}}_2}}}$$.
• D) The partial derivative of the function $$f(x,y,z) = 3xyz + 2{x^2} + {z^2}$$ with respect to third variable is $${f_z} = 2z$$