BITSAT 2012 Paper

Ax2+By2 = 1 ... (1)
Ax + By

dy

dx

= 0 ... (2)
A + By

d2y

dx2

+ B(

dy]

dx

)2 = 0 ... (3)
From (2) and (3)
x {−By

d2y

dx2

−B(

dy

dx

)2} + By

dy

dx

= 0
Dividing both sides by –B, we get
xy

d2y

dx2

+ x (

dy

dx

)2 - y

dy

dx

= 0
Which is a DE of order 2 and degree 1