ParabolaHard
Question
If the line x - 1 = 0 is the directrix of the parabola y2 = kx - 8, then one of the values of k is
Options
A.
B.8
C.4
D.
Solution
Given, y2 = kx - 8
⇒
Shifting the origin Y2 = kX where Y = y, X = x - 8 / k
Directrix of standard parabola is
Directrix of original parabola is
Now, x =1 also coincides with
On solving, we get k = 4
⇒
Shifting the origin Y2 = kX where Y = y, X = x - 8 / k
Directrix of standard parabola is
Directrix of original parabola is
Now, x =1 also coincides with
On solving, we get k = 4
Create a free account to view solution
View Solution FreeMore Parabola Questions
If the focus of the parabola (y - λ)2 = 4(x - λ) always lies between the lines 2x + y = 1 and 2x + y = 3 then ...The equation of a straight line passing through the point (3, 6) and cutting the curve y = √x orthogonally is -...If the tangents and normals at the extremities of a focal chord of a parabola intersect at (x1, y1) and (x2, y2) respect...The co-ordinates of a point on the parabola 2y = x2 which is nearest to the point (0, 3) is...If the chord joining the points $P_1(x_1, y_1)$ and $P_2(x_2, y_2)$ on the parabola $y^2 = 12x$ subtends a right angle a...