Quantrex Quantrex AcademyJEE · NEET · NDA PYQs with solutions Open app
NTA Abhyas 2020
Exam
NTA Abhyas
Year
2020
Subject
Mathematics
Chapter
Parabola

NTA Abhyas 2020 · Mathematics · Parabola

If the line y - 2 = 0 is the directrix of the parabola x ^ 2 - ky +...

If the line y−2=0y - 2 = 0 is the directrix of the parabola x2−ky+32=0,k≠0{x}^{2} - ky + 32 = 0, k \ne 0 and the parabola intersects the circle x2+y2=8{x}^{2} + {y}^{2} = 8 at two real distinct points, then the absolute value of kk is

Correct answer

16

Step-by-step solution

x2−ky+32=0{x}^{2} - ky + 32 = 0
⇒x2=k(y−32k)⇒ {x}^{2} = k\left(y - \dfrac{32}{k}\right)
Put, x=X,y−32k=Yx = X, y - \dfrac{32}{k} = Y
The equation of directrix is Y+k4=0Y + \dfrac{k}{4} = 0
i.e. y−32k+k4=0y - \dfrac{32}{k} + \dfrac{k}{4} = 0
But, y−2=0y - 2 = 0 is the directrix.
⇒32k−k4=2⇒ \dfrac{32}{k} - \dfrac{k}{4} = 2
⇒k2+8k−128=0⇒ {k}^{2} + 8k - 128 = 0
⇒k=−16⇒ k = - 16 or k=8k = 8
For k=8,k = 8, the parabola is x2=8(y−4){x}^{2} = 8\left(y - 4\right) which does not intersect the circle.
For k=−16,k = - 16, the parabola is x2=−16(y+2){x}^{2} = - 16\left(y + 2\right) which intersects the circle at two real distinct points.
⇒⇒ Absolute value of k=∣−16∣=16k = \left|- 16\right| = 16
Practice Parabola on Quantrex Academy →

More from Parabola

Let T be the tangent to the parabola y^2 = 16x at the point (64, 32) . Let L be the… JEE Advanced 2026Let O be the vertex of the parabola y^2=4x and its chords OP and OQ are perpendicular to… JEE Main 2026Let chord PQ of length 3 13 of the parabola y^2 = 12x be such that the ordinates of… JEE Main 2026Let the point P be the vertex of the parabola y = x^2 - 6x + 12 . If a line passing… JEE Main 2026Let the directrix of the parabola P: y^2 = 8x , cut x -axis at the point A . Let B(α, β)… JEE Main 2026Let A,B and C be the vertices of a variable right angled triangle inscribed in the… JEE Main 2026Consider the parabola P : y^2 = 4kx and the ellipse E : (x^2)/(a^2) + (y^2)/(b^2) = 1 .… JEE Main 2026Let the parabola y = x^2 + px + q passing through the point (1, -1) be such that the… JEE Main 2026Let A be the focus of the parabola y^ 2 =8 x . Let the line y=m x+c intersect the… JEE Main 2026Let the image of parabola x^ 2 =4 y , in the line x-y=1 be (y+a)^ 2 =b(x-c) , a, b, c ∈… JEE Main 2026An equilateral triangle OAB is inscribed in the parabola y^ 2 =4 x with the vertex O at… JEE Main 2026Let the locus of the mid-point of the chord through the origin O of the parabola y^ 2 =4… JEE Main 2026If the chord joining the points P_ 1 (x_ 1 , y_ 1 ) and P_ 2 (x_ 2 , y_ 2 ) on the… JEE Main 2026Let y^ 2 =12 x be the parabola with its vertex at O. Let P be a point on the parabola and… JEE Main 2026Let one end of a focal chord of the parabola y^ 2 =16 x be (16,16) . If P(α, β) divides… JEE Main 2026Let O be the vertex of the parabola x^ 2 =4 y and Q be any point on it. Let the locus of… JEE Main 2026 Full Parabola list Parabola JEE Maths PYQsJEE Mathematics PYQs All NTA Abhyas JEE Main PYQs