Differential Equations Question 266

Question: What is the differential equation for $ y^{2}=4a(x-a) $ -

Options:

A) $ yy’-2xyy’+y^{2}=0 $

B) $ yy’(yy’+2x)+y^{2}=0 $

C) $ yy’(yy’-2x)+y^{2}=0 $

D) $ yy’-2xyy’+y=0 $

Show Answer

Answer:

Correct Answer: C

Solution:

[c] Given curve is $ y^{2}=4a(x-a) $

  • (i) On differentiating w.r.t. x we get $ 2yy’=4a $
    $ \Rightarrow a=\frac{yy’}{2} $ O putting the value of a in Eq. (i) we get $ y^{2}=4( \frac{yy’}{2} )( x-\frac{yy’}{2} )=yy’(2x-yy’) $
    $ \Rightarrow yy’(yy’-2x)+y^{2}=0 $