Conic Sections Question 45
Question: The equation of the directrix of the parabola $ x^{2}+8y-2x=7 $ is
[UPSEAT 2004]
Options:
A) $ y=3 $
B) $ y=-3 $
C) $ y=2 $
D) $ y=0 $
Show Answer
Answer:
Correct Answer: A
Solution:
Given, equation of parabola is $ x^{2}+8y-2x=7 $
$ \Rightarrow $ $ x^{2}-2x+8y-7=0 $
$ \Rightarrow $ $ x^{2}-2x+1+8y-7-1=0 $
$ \Rightarrow $ $ {{(x-1)}^{2}}+8y=8 $
$ \Rightarrow $ $ {{(x-1)}^{2}}=-8(y-1) $
$ \Rightarrow $ $ {{(x-1)}^{2}}=-4.2(y-1) $
Here, $ a=2 $ .
$ \therefore $ Equation of directrix is $ y-1=2 $ i.e., $ y=3 $ .
BETA
