JEE Main On 08 April 2018 Question 5
Question: If the curves $ y^{2}=6x,9x^{2}+by^{2}=16 $ intersect each other at right angles, then the value of b is: [JEE Main Online 08-04-2018]
Options:
A) 4
B) $ \frac{9}{2} $
C) 6
D) $ \frac{7}{2} $
Show Answer
Answer:
Correct Answer: B
Solution:
$ 2yy=6 $ $ 18x+2byy=0 $
$ m _1m _2=-1 $ $ \frac{3}{y}\cdot ( \frac{-9x}{by} )=-1 $
$ \frac{x}{y^{2}}=\frac{b}{27}=\frac{1}{6} $
$ \Rightarrow b=\frac{9}{2} $
