Tag: tracing of the parabola

Questions Related to tracing of the parabola

Multiple choice mathematics and statistics parabola tracing of the parabola definitions related to parabola introduction to parabola

The focus of the parabola $y ^ { 2 } = 4 y - 4 x$ is

  1. $( 0,2 )$
  2. $( 1,2 )$
  3. $( 4,2 )$
  4. $( 1,3 )$
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

$\Rightarrow y^2 = 4y - 4x$

$\Rightarrow y^2 - 4y = -4x$
$\Rightarrow y^2 - 4y + 4 = -4x + y$
$\Rightarrow (y - 2)^2 = -4 (x - 1)$
vertex = $(1, 2)$
$\dfrac{1}{4 p} = \dfrac{-1}{4} \rightarrow p = -1$
$\therefore$ Focus = $(-1 + 1, 2 + 0) = (0, 2)$

Multiple choice mathematics and statistics parabola tracing of the parabola definitions related to parabola introduction to parabola

The equation of the directrix of the parabola, $y ^ { 2 } + 4 y + 4 x + 2 = 0$ is -

  1. $x = - 1$
  2. $x = 1$
  3. $x = - \dfrac {3 }{ 2}$
  4. $x = \dfrac {3 }{ 2}$
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation
Given equation of parabola
$y^2+4y+4x+2=0$
or $(y+2)^2+4x+2=0$
or $(y+2)^2=-4(x-12)$
Its directrix  is x12x−12=1=1
or x=32
Hence D is the correct answer.

y2+4y+4x+2=