Published by:
CGP EDU Academic Team
Published on: August 14, 2026
If the line 2x –1 = 0 is the directrix of the parabola y 2 – kx + 6 = 0 then one of the values
of k is :
A
– 6
B
6
C
D
– 
Text Solution
Verified by ExpertsThe correct answer is:
A
y 2 – kx + 6
y 2 = kx – 6
y 2 = k 
Directrix
x – 
= – 
x = 
– 
.......(i)
But directrix is given
x = 
.......... (ii)
comparing
– 
= 
⇒ 
= 
⇒ 24 – k 2 = 2k
⇒ k 2 + 2k – 24 = 0
⇒ (k + 6)(k – 4) = 0
⇒ k = – 6, k = 4
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