Explore topic-wise MCQs in Joint Entrance Exam - Main (JEE Main).

This section includes 8666 Mcqs, each offering curated multiple-choice questions to sharpen your Joint Entrance Exam - Main (JEE Main) knowledge and support exam preparation. Choose a topic below to get started.

3051.

The solution of \[\frac{dy}{dx}=\frac{{{x}^{2}}+{{y}^{2}}+1}{2xy}\] satisfying y(1)=1 is given by

A. a system of parabolas
B. a system of circles
C. \[{{y}^{2}}=x(1+x)-1\]
D. \[{{(x-2)}^{2}}+{{(y-3)}^{2}}=5\]
Answer» D. \[{{(x-2)}^{2}}+{{(y-3)}^{2}}=5\]
3052.

Solution of the differential equation \[(y+x\sqrt{xy}(x+y))\,dx+(y\sqrt{xy}(x+y)-x)dy=0\] is

A. \[\frac{{{x}^{2}}+{{y}^{2}}}{2}+{{\tan }^{-1}}\sqrt{\frac{y}{x}=c}\]
B. \[\frac{{{x}^{2}}+{{y}^{2}}}{2}+2{{\tan }^{-1}}\sqrt{\frac{x}{y}=c}\]
C. \[\frac{{{x}^{2}}+{{y}^{2}}}{2}+2{{\cot }^{-1}}\sqrt{\frac{x}{y}=c}\]
D. None of these
Answer» C. \[\frac{{{x}^{2}}+{{y}^{2}}}{2}+2{{\cot }^{-1}}\sqrt{\frac{x}{y}=c}\]
3053.

The solution of (y + x + 5) dy = (y - x + 1) dx is

A. \[\log ({{(y+3)}^{2}}+{{(x+2)}^{2}})+ta{{n}^{-1}}\frac{y+3}{y+2}+C\]
B. \[\log ({{(y+3)}^{2}}+{{(x-2)}^{2}})+ta{{n}^{-1}}\frac{y-3}{x-2}=C\]
C. \[\log ({{(y+3)}^{2}}+{{(x+2)}^{2}})+2ta{{n}^{-1}}\frac{y+3}{x+2}=C\]
D. \[\log ({{(y+3)}^{2}}+{{(x+2)}^{2}})-2ta{{n}^{-1}}\frac{y+3}{x+2}=C\]
Answer» D. \[\log ({{(y+3)}^{2}}+{{(x+2)}^{2}})-2ta{{n}^{-1}}\frac{y+3}{x+2}=C\]
3054.

Solution of \[\frac{dy}{dx}+2xy=y\] is

A. \[y=c{{e}^{x-{{x}^{2}}}}\]
B. \[y=c\,{{e}^{{{x}^{2}}-x}}\]
C. \[y=c\,{{e}^{x}}\]      
D. \[y=c\,{{e}^{-{{x}^{2}}}}\]
Answer» B. \[y=c\,{{e}^{{{x}^{2}}-x}}\]
3055.

The differential equation of all parabolas whose axis are parallel to the y-axis is

A. \[\frac{{{d}^{3}}y}{d{{x}^{3}}}=0\]
B. \[\frac{{{d}^{2}}x}{d{{y}^{2}}}=C\]
C. \[\frac{{{d}^{3}}y}{d{{x}^{3}}}+\frac{{{d}^{2}}x}{d{{y}^{2}}}=0\]
D. \[\frac{{{d}^{2}}y}{d{{x}^{2}}}+2\frac{dy}{dx}=C\]
Answer» B. \[\frac{{{d}^{2}}x}{d{{y}^{2}}}=C\]
3056.

If \[y=\frac{x}{\log \left| cx \right|}\] (where c is an arbitrary constant) I the general solution of the differential equation \[dy/dx=y/x+\phi (x/y)\] then the function \[\phi (x/y)\]is

A. \[{{x}^{2}}/{{y}^{2}}\]        
B. \[-{{x}^{2}}/{{y}^{2}}\]
C. \[{{y}^{2}}/{{x}^{2}}\]        
D. \[-{{y}^{2}}/{{x}^{2}}\]
Answer» E.
3057.

The solution of the differential equation\[y(2{{x}^{4}}+y)\frac{dy}{dx}=(1-4x{{y}^{2}}){{x}^{2}}\] is given by

A. \[3{{({{x}^{2}}y)}^{2}}+{{y}^{3}}-{{x}^{3}}=c\]
B. \[x{{y}^{2}}+\frac{{{y}^{3}}}{3}-\frac{{{x}^{3}}}{3}+c=0\]
C. \[\frac{2}{3}y{{x}^{5}}+\frac{{{y}^{3}}}{3}=\frac{{{x}^{3}}}{3}-\frac{4x{{y}^{3}}}{3}+c\]
D. None of these
Answer» B. \[x{{y}^{2}}+\frac{{{y}^{3}}}{3}-\frac{{{x}^{3}}}{3}+c=0\]
3058.

Orthogonal trajectories of family of the curve \[{{x}^{2/3}}+{{y}^{2/3}}={{a}^{2/3}}\], where a is any arbitrary constant, is

A. \[{{x}^{2/3}}-{{y}^{2/3}}=c\]
B. \[{{x}^{4/3}}-{{y}^{4/3}}=c\]
C. \[{{x}^{4/3}}+{{y}^{4/3}}=c\]
D. \[{{x}^{1/3}}-{{y}^{1/3}}=c\]
Answer» C. \[{{x}^{4/3}}+{{y}^{4/3}}=c\]
3059.

Tangent to a curve intercepts the y-axis at a point P. A line perpendicular to this tangent through P passes through another point (1, 0). The differential equation of the curve

A. \[y\frac{dy}{dx}-x{{\left( \frac{dy}{dx} \right)}^{2}}=1\]
B. \[\frac{x{{d}^{2}}y}{d{{x}^{2}}}+{{\left( \frac{dy}{dx} \right)}^{2}}=0\]
C. \[y\frac{dx}{dy}+x=1\]
D. None of these
Answer» B. \[\frac{x{{d}^{2}}y}{d{{x}^{2}}}+{{\left( \frac{dy}{dx} \right)}^{2}}=0\]
3060.

  The solution of the differential equation \[\frac{dy}{dx}=\frac{3{{x}^{2}}{{y}^{4}}+2xy}{{{x}^{2}}-2{{x}^{3}}{{y}^{3}}}\] is

A. \[\frac{{{y}^{2}}}{x}-{{x}^{3}}{{y}^{2}}=c\]
B. \[\frac{{{x}^{2}}}{{{y}^{2}}}+{{x}^{3}}{{y}^{3}}=c\]
C. \[\frac{{{x}^{2}}}{y}+{{x}^{3}}{{y}^{2}}=c\]
D. \[\frac{{{x}^{2}}}{3y}-{{x}^{3}}{{y}^{2}}=c\]
Answer» D. \[\frac{{{x}^{2}}}{3y}-{{x}^{3}}{{y}^{2}}=c\]
3061.

The solution of differential equation \[(2y+x{{y}^{3}})dx+(x+{{x}^{2}}{{y}^{2}})dy=0\] is

A. \[{{x}^{2}}y+\frac{{{x}^{3}}{{y}^{3}}}{3}=c\]
B. \[x{{y}^{2}}+\frac{{{x}^{3}}{{y}^{3}}}{3}=c\]
C. \[{{x}^{2}}y+\frac{{{x}^{4}}{{y}^{4}}}{4}=c\]
D. none of these
Answer» B. \[x{{y}^{2}}+\frac{{{x}^{3}}{{y}^{3}}}{3}=c\]
3062.

The general solution of the equation \[\frac{dy}{dx}=1+xy\] is

A. \[y=c{{e}^{-{{x}^{2}}/2}}\]
B. \[y=c{{e}^{{{x}^{2}}/2}}\]
C. \[y=(x+c){{e}^{-{{x}^{2}}/2}}\]
D. None of these
Answer» E.
3063.

If integrating factor of \[x(1-{{x}^{2}})dy+(2{{x}^{2}}y-y-a{{x}^{3}})dx=0\] is \[_{e}\int pdx\], then P is equal to

A. \[\frac{2{{x}^{2}}-a{{x}^{3}}}{x(1-{{x}^{2}})}\]   
B. \[2{{x}^{3}}-1\]
C. \[\frac{2{{x}^{2}}-a}{a{{x}^{3}}}\]
D. \[\frac{2{{x}^{2}}-1}{x(1-{{x}^{2}})}\]
Answer» E.
3064.

The solution of the differential equation \[{{x}^{2}}\frac{dy}{dx}\cos \frac{1}{x}-y\sin \frac{1}{x}=-1\], where \[y\to -1\,\,as\,\,x\to \infty \]is

A. \[y=\sin \frac{1}{x}-\cos \frac{1}{x}\]
B. \[y=\frac{x+1}{x\sin \frac{1}{x}}\]
C. \[y=\cos \frac{1}{x}+sin\frac{1}{x}\]
D. \[y=\frac{x+1}{x\cos 1/x}\]
Answer» B. \[y=\frac{x+1}{x\sin \frac{1}{x}}\]
3065.

The solution to the differential equation\[y\log y+xy'=0\], where \[y(1)=e\], is

A. \[x(log\,y)=1\]   
B. \[xy(log\,y)=1\]
C. \[{{(log\,y)}^{2}}=2\] 
D. \[\log y+\left( \frac{{{x}^{2}}}{2} \right)y=1\]
Answer» B. \[xy(log\,y)=1\]
3066.

If \[x\ne 0\], \[y\ne 0\], \[z\ne 0\] and , then \[{{x}^{-1}}+{{y}^{-1}}+{{z}^{-1}}\] is equal to

A.  \[-\,1\]             
B.  \[-\,2\]
C.  \[-\,3\]             
D.  none of these
Answer» D.  none of these
3067.

The value of the determinant\[\left| \begin{matrix}    1 & 1 & 1  \\    ^{m}{{C}_{1}} & ^{m+1}{{C}_{1}} & ^{m+2}{{C}_{1}}  \\    ^{m}{{C}_{2}} & ^{m+1}{{C}_{2}} & ^{m+2}{{C}_{2}}  \\ \end{matrix} \right|\]

A.  1        
B.  -1
C.  0                    
D.  none of these
Answer» B.  -1
3068.

If a, b, and c are nonzero real number then \[\Delta =\left| \begin{matrix}    {{b}^{2}}{{c}^{2}} & bc & b+c  \\    {{c}^{2}}{{a}^{2}} & ca & c+a  \\    {{a}^{2}}{{b}^{2}} & ab & a+b  \\ \end{matrix} \right|\]is equal to

A.  abc                 
B.  \[{{a}^{2}}{{b}^{2}}{{c}^{2}}\]
C.  bc+ca+ab       
D.  none of these
Answer» E.
3069.

The value of the determinant\[\left| \begin{matrix}    kb & {{k}^{^{2}}}+{{a}^{2}} & 1  \\    kb & {{k}^{2}}+{{b}^{2}} & 1  \\    kc & {{k}^{2}}+{{c}^{2}} & 1  \\ \end{matrix} \right|\]is

A.  \[k(a+b)(b+c)(c+a)\]
B.  \[k\,abc({{a}^{2}}+{{b}^{2}}+{{c}^{2}})\]
C.  \[k(a-b)(b-c)(c-a)\]
D.  \[k(a+b-c)(b+c-a)(c+a-b)\]
Answer» D.  \[k(a+b-c)(b+c-a)(c+a-b)\]
3070.

If \[f(x)=a+bx+c{{x}^{2}}\] and \[\alpha ,\beta ,\gamma \]are the roots of the equation\[{{x}^{3}}=1,\]then is equal to

A.  \[f(\alpha )+f(\beta )+f(\gamma )\]
B.  \[f(\alpha )f(\beta )+f(\beta )\]\[f(\gamma )+f(\gamma )\]\[f(\alpha )\]
C.  \[f(\alpha )f(\beta )f(\gamma )\]
D.  \[f(\alpha )f(\beta )f(\gamma )\]
Answer» C.  \[f(\alpha )f(\beta )f(\gamma )\]
3071.

If , then z is

A.  purely real
B.  purely imaginary
C.  \[a+ib,\]where \[a\ne 0,\]\[b\ne 0,\]
D.  \[a+ib,\]where b = 4
Answer» C.  \[a+ib,\]where \[a\ne 0,\]\[b\ne 0,\]
3072.

If \[{{\Delta }_{1}}=\left| \begin{matrix}    x & b & b  \\    a & x & b  \\    a & a & x  \\ \end{matrix} \right|\] and \[{{\Delta }_{2}}=\left| \begin{matrix}    x & b  \\    a & x  \\ \end{matrix} \right|\]are the given determinants, then

A.  \[{{\Delta }_{1}}=3{{({{\Delta }_{2}})}^{2}}\]
B.  \[\frac{d}{dx}({{\Delta }_{1}})=3({{\Delta }_{2}})\]
C.  \[\frac{d}{dx}({{\Delta }_{1}})=3{{({{\Delta }_{2}})}^{2}}\]
D.  \[{{\Delta }_{1}}=3{{\Delta }_{2}}^{3/2}\]
Answer» C.  \[\frac{d}{dx}({{\Delta }_{1}})=3{{({{\Delta }_{2}})}^{2}}\]
3073.

The determinant is equal to

A.  \[\left| \begin{matrix}    bx+ay & cx+by  \\    b'x+a'y & c'x+b'y  \\ \end{matrix} \right|\]
B.  \[\left| \begin{matrix}    ax+by & bx+cy  \\    a'x+b'y & b'x+c'y  \\ \end{matrix} \right|\]
C.  \[\left| \begin{matrix}    bx+cy & ax+by  \\    b'x+c'y & a'x+b'y  \\ \end{matrix} \right|\]
D.  \[\left| \begin{matrix}    ax+by & bx+cy  \\    a'x+b'y & b'x+c'y  \\ \end{matrix} \right|\]
Answer» E.
3074.

If the value of the determinant \[\left| \begin{matrix}    a & 1 & 1  \\    1 & b & 1  \\    1 & 1 & c  \\ \end{matrix} \right|\] is positive, then (a, b, c > 0)

A.  \[abc>1\]         
B.  \[abc>-\,8\]
C.  \[abc<-\,8\]      
D.  \[abc>-\,2\]
Answer» C.  \[abc<-\,8\]      
3075.

If \[{{l}^{2}}_{1}+{{m}_{1}}^{2}+{{n}_{1}}^{2}=1\], etc. and \[{{l}_{1}}{{l}_{2}}+{{m}_{1}}{{m}_{2}}+{{n}_{1}}{{n}_{2}}=0\], etc. and \[\Delta =\left| \begin{matrix}    {{l}_{1}} & {{m}_{1}} & {{n}_{1}}  \\    {{l}_{2}} & {{m}_{2}} & {{n}_{2}}  \\    {{l}_{3}} & {{m}_{3}} & {{n}_{3}}  \\ \end{matrix} \right|\], then

A.  \[\left| \Delta  \right|\]=3           
B.  \[\left| \Delta  \right|\]=2
C.  \[\left| \Delta  \right|\]=1           
D.  \[\Delta \]=0
Answer» D.  \[\Delta \]=0
3076.

The value of the determinant\[\left| \begin{matrix}   ^{n}{{C}_{r-1}} & ^{n}{{C}_{r}} & (r+1) & ^{n+2}{{C}_{r+1}}  \\   ^{n}{{C}_{r}} & ^{n}{{C}_{r+1}} & (r+2) & ^{n+2}{{C}_{r+2}}  \\   ^{n}{{C}_{r+1}} & ^{n}{{C}_{r+2}} & (r+3) & ^{n+2}{{C}_{r+3}}  \\\end{matrix} \right|\] is

A. \[{{n}^{2}}+n-1\]      
B.  0
C. \[^{n+3}{{C}_{r+3}}\]         
D. \[^{n}{{C}_{r-1}}{{+}^{n}}{{C}_{r}}{{+}^{n}}{{C}_{r+1}}\]
Answer» C. \[^{n+3}{{C}_{r+3}}\]         
3077.

If \[{{a}_{1}},{{a}_{2}}...{{a}_{n}}....\]form a G.P. and \[{{a}_{i}}\]>0, for all \[i\ge 1\], then\[\left| \begin{matrix}    \log {{a}_{n}} & \log {{a}_{n+1}} & \log {{a}_{n+2}}  \\    \log {{a}_{n+3}} & \log {{a}_{n+4}} & \log {{a}_{n+5}}  \\    \log {{a}_{n+6}} & \log {{a}_{n+7}} & \log {{a}_{n+8}}  \\ \end{matrix} \right|\]is equal to

A.  0                    
B.  1
C.  2        
D.  3
Answer» B.  1
3078.

Suppose and. Then

A. D'=D
B. D'=D(1-pqr)
C. D'=D(1+p+q+r)
D. D'=D(1+pqr)
Answer» E.
3079.

If \[\left| \begin{matrix}    {{x}^{n}} & {{x}^{n+2}} & {{x}^{2n}}  \\    1 & {{x}^{a}} & a  \\    {{x}^{n+5}} & {{x}^{a+6}} & {{x}^{2n+5}}  \\ \end{matrix} \right|=0,\forall x\in R\] where \[n\in N\], then value of a is

A.  n                    
B.  n-1
C.  n+1                
D.  none of these
Answer» D.  none of these
3080.

If , then

A.  \[f'(x)=0and\,f''(x)=0\]has one common root
B.  \[f(x)=0\,\,and\,f'(x)=0\]has one common root
C.  sum of roots of \[f(x)\]=0 is \[-\,3\,a\]
D.  none of these
Answer» C.  sum of roots of \[f(x)\]=0 is \[-\,3\,a\]
3081.

In triangle ABC, if \[\left| \begin{matrix}    1 & 1 & 1  \\    \cos \frac{A}{2} & \cot \frac{A}{2} & \cot \frac{C}{2}  \\    \tan \frac{B}{2}+\tan \frac{C}{2} & \tan \frac{C}{2}+\tan \frac{A}{2} & \tan \frac{A}{2}+\tan \frac{B}{2}  \\ \end{matrix} \right|=0\] then the triangle must be

A.  equilateral
B.  isosceles
C.  obtuse angled
D.  none of these
Answer» C.  obtuse angled
3082.

The function \[f(x)\] defined by\[f(x)=\left\{ \begin{matrix}    {{\log }_{(4x-3)}}({{x}^{2}}-2x+5),\,\,\,\,\,\,\frac{3}{4}

A. is continuous at x=1
B. is discontinuous at x=1 since \[f({{1}^{+}})\]does not exist though \[f({{1}^{-}})\]exists
C. is discontinuous at x=1 since \[f({{1}^{-}})\]does not exist thought \[f({{1}^{+}})\]exists
D. is discontinuous at x=1 since neither \[f({{1}^{+}})\]nor \[f({{1}^{-}})\]exists.
Answer» E.
3083.

If \[f(x)=\left\{ \begin{matrix}    x+2,\,\,\,\,\,\,\,\,\,x

A. 1                     
B. 2
C. 3                     
D. none of these
Answer» B. 2
3084.

A point where function \[f(x)=[sin[x]]\] is not continuous in \[(0,2\pi )\], [.] denotes the greatest integer \[\le x\], is

A. (3, 0)    
B. (2, 0)
C. (1, 0)    
D. none of these
Answer» E.
3085.

  Let \[f(x)=\left\{ \begin{matrix}    \frac{x-4}{\left| x-4 \right|}+a,\,\,\,\,\,\,x4  \\ \end{matrix} \right.\] Then \[f(x)\] is continuous at x=4

A. \[a=0,\text{ }b=0\]       
B. \[a=1,\text{ }b=1\]
C. \[a=-\,1,\text{ }b=1\]    
D. \[a=1,\text{ }b=-1\]
Answer» E.
3086.

The function \[f(x)=\frac{{{({{3}^{x}}-1)}^{2}}}{\sin x\cdot \ln \,(1+x)},x\ne 0\], is continuous at x=0. Then the value of f(0) is

A. \[2{{\log }_{e}}3\]        
B. \[{{(2{{\log }_{e}}3)}^{2}}\]
C. \[{{\log }_{e}}6\]          
D. none of these
Answer» C. \[{{\log }_{e}}6\]          
3087.

The value of f(0) so that the function \[f(x)=\frac{2x-{{\sin }^{-1}}x}{2x+{{\tan }^{-1}}x}\]is continuous at each point in its domain, is equal to

A. 2                     
B. 44256
C. 2/3                   
D. -0.333333333333333
Answer» C. 2/3                   
3088.

The set of all points where \[f(x)=\sqrt[3]{{{x}^{2}}\left| x \right|}-\left| x \right|-1\]is not differentiable is

A. {0}                  
B. \[\left\{ -1,\text{ }0,\text{ }1 \right\}\]
C. {0, 1}  
D. none of these
Answer» E.
3089.

\[f(x)=\underset{n\to \infty }{\mathop{\lim }}\,\frac{{{(x-1)}^{2n}}-1}{{{(x-1)}^{2n}}+1}\]is discontinuous at

A. \[x=0\]only       
B. \[x=2\]only
C. \[x=0\]and 2     
D. none of these
Answer» D. none of these
3090.

If \[f(x)=\left\{ \begin{matrix}    {{x}^{2}}-ax+3,\,\,\,x\,\,\text{is}\,\,\text{rational}  \\    2-x,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,x\,\,\text{is}\,\,\text{irrational}  \\ \end{matrix} \right.\]is continuous at exactly two points, then the possible values of a are

A. \[(2,\infty )\]      
B. \[(-\infty ,3)\]
C. \[(-\infty ,-3)\cup (3,\infty )\]
D. none of these
Answer» D. none of these
3091.

If \[f(x)=\left\{ \begin{matrix}    x-1,\,\,\,\,\,\,\,x

A. \[f(\left| x \right|)\]is discontinuous at x=0
B. \[f(\left| x \right|)\]is differentiable at x=0
C. \[|f(x)|\]is non-differentiable at x=0, 2
D. \[|f(x)|\]is continuous at x=0
Answer» D. \[|f(x)|\]is continuous at x=0
3092.

If \[f(x)=\left\{ \begin{matrix}    {{e}^{{{x}^{2}}+x}}\,\,\,\,\,x>0  \\    ax+b,\,\,x\le 0  \\ \end{matrix} \right.\]is differentiable at x=0, then

A. \[a=1,\text{ }b=-\,1\]
B. \[a=-1,\text{ }b=1\]
C. \[a=1,\text{ }b=1\]       
D. \[a=-\,1,\text{ }b=-\,1\]
Answer» D. \[a=-\,1,\text{ }b=-\,1\]
3093.

If \[f(x)=\left\{ \begin{matrix}    {{x}^{3}},\,\,{{x}^{2}}1  \\ \end{matrix} \right.\], then \[f(x)\] is differentiable at

A. \[(-\infty ,\infty )-\{1\}\]  
B. \[(-\infty ,\infty )\tilde{\ }\{1,-1\}\]
C. \[(-\infty ,\infty )\tilde{\ }\{1,-1,0\}\]
D. \[(-\infty ,\infty )\tilde{\ }\{-1\}\]
Answer» C. \[(-\infty ,\infty )\tilde{\ }\{1,-1,0\}\]
3094.

Which of the following function is not differentiable at x=1?

A. \[f(x)=({{x}^{2}}-1)\left| (x-1)(x-2) \right|\]
B. \[f(x)=sin(\left| x-1 \right|)-\left| x-1 \right|\]
C. \[f(x)=\tan (\left| x-1 \right|)-\left| x-1 \right|\]
D. None of these
Answer» D. None of these
3095.

\[f(x)=\left\{ \begin{matrix}    \frac{x}{2{{x}^{2}}+\left| x \right|,}\,\,x\ne 0  \\    1.\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,x=0  \\ \end{matrix} \right.\]. Then \[f(x)\] is

A. continuous but non-differentiable at x=0
B. differentiable at x=0
C. discontinuous at x=0
D. none of these
Answer» D. none of these
3096.

The number of values of \[x\in [0,2]\] at which \[f(x)=\left| x-\frac{1}{2} \right|+\left| x-1 \right|+\tan x\] is not differentiable is

A. 0                     
B. 1
C. 3                     
D. none of these
Answer» D. none of these
3097.

If \[f(x)={{x}^{3}}\sgn x,\]then

A. f is derivable at x=0
B. f is continuous but not derivable at x=0
C. LHD at x=0 is 1
D. RHD at x=0 is 1
Answer» B. f is continuous but not derivable at x=0
3098.

If \[f(x)=\frac{{{x}^{2}}-bx+25}{{{x}^{2}}-7x+10}\] for \[x\ne 5\] is continuous at x=5, then the value of \[f(5)\] is

A. 0                     
B. 5
C. 10                    
D. 25
Answer» B. 5
3099.

Which of the following functions have finite number of points of discontinuity in R ([.] represents the greatest integer function)?

A. \[\operatorname{tanx}\]
B. \[x[x]\]
C. \[\frac{\left| x \right|}{x}\]         
D. \[\sin [\pi x]\]  
Answer» D. \[\sin [\pi x]\]  
3100.

The vertex of a parabola is the point, (a,b) and the latus rectum is of length, l. the axis of the parabola is parallel to the y-axis and the parabola is concave upward, then its equation is

A.  \[{{(x+a)}^{2}}=\frac{1}{2}(2y-2b)\]
B.  \[{{(x-a)}^{2}}=\frac{1}{2}(2y-2b)\]
C.  \[{{(x+a)}^{2}}=\frac{1}{4}(2y-2b)\]
D.  \[{{(x-a)}^{2}}=\frac{1}{8}(2y-2b)\]
Answer» B.  \[{{(x-a)}^{2}}=\frac{1}{2}(2y-2b)\]