Tag: mathematics and statistics

Questions Related to mathematics and statistics

The locus of the midpoint of the line segment joining the focus to a  moving point on the parabola y$^2$ - 4ax is another parabola with directrix

  1. x = - a

  2. x = a

  3. x = 0

  4. x = $\dfrac{a}{2}$


Correct Option: A

Equation of the directrix of the parabola $4y^2-6x-4y-5=0$ is 

  1. $8x+11=0$

  2. $8x-11=0$

  3. $11x+8=0$

  4. $11x-8=0$


Correct Option: A

The equation of the directrix of the parabola $y= x^2-2x+3$ is 

  1. $y= 1/4$

  2. $y= 1/4$

  3. $y= 7/4$

  4. $y= - 7/4$


Correct Option: B

The focus of the parabola $x^2 -4x+2y+8=0$ is 

  1. $(3/2, -2)$

  2. $(5/2, -2)$

  3. $(2, -3/2, )$

  4. $(2, -5/2, )$


Correct Option: A

The equation of the directrix of the parabolas $x=-2at,\ y=-at^{2},\ t\ \epsilon \ R$ is

  1. $x-a=0$

  2. $y-a=0$

  3. $x+a=0$

  4. $y+a=0$


Correct Option: A

The angle of intersection at the origin to the curves ${ y }^{ 2 }=4x$ and ${ x }^{ 2 }=4y$ is :

  1. $\pi $

  2. $\dfrac{ \pi }{ 3}$

  3. $\dfrac{ \pi }{ 6 }$

  4. $\dfrac{ \pi }{ 2 }$


Correct Option: D
Explanation:
Given  $y^2=4x$

Differentiating w.r.t. $x$, we get,

$2y\dfrac{dy}{dx}=4$

$\dfrac{dy}{dx}=\dfrac2y.......1$

$x^2=4y$

Differentiating w.r.t. $x$, we get,

$2x=4\dfrac{dy}{dx}$

$\dfrac{dy}{dx}=\dfrac{x}{2}...........2$

So the slope of tangent at $(0,0)$ of $(1)$ is Parallel to $y$ axis 

And the slope of tangent at $(0,0)$ of $(2)$ is Parallel to $x$ axis 

So the angle between them is $\dfrac{\pi}{2}$ 

if the vertex and the focus of the parabola are $(-1, -1) & (2, 3)$ respectively, then the equation of the directrix is

  1. $3x + 2y + 14 = 0$

  2. $3x + 2y - 25 = 0$

  3. $2x - 3y + 10 = 0$

  4. $x - y + 5 = 0$


Correct Option: A

The parametric equation of a parabola is $x=t^{2}+1, y=2t+1$. The Cartesian equation of its directrix is 

  1. $x=0$

  2. $x+1=0$

  3. $y=0$

  4. $none\ of\ these$


Correct Option: A

$TP$ and $TQ$ are tangents to parabola $y^{2}=4x$ and normal at $P$ and $Q$ intersect at a point $R$ on the curve. The locus of the center of the circle circumscribing $\Delta TPQ$ is parabola whose

  1. Vertex is $\left(1,0\right)$.

  2. Foot of directrix is $\left(\dfrac{7}{8},0\right)$

  3. Length of latus-rectum is $\dfrac{1}{4}$.

  4. Focus is $\left(\dfrac{9}{8},0\right)$


Correct Option: A

For parabola $x^{ 2 } + y^{ 2 } + 2xy 6x 2y + 3 = 0$ the focus is

  1. $\left( 1, -1\right)$

  2. $\left( -1, 1\right)$

  3. $\left( 3, 1\right)$

  4. $None of these$


Correct Option: A