6. Form the differential equation of the family of circles touching the y-axis at origin.
If the circle touches y-axis at the origin then the centre of the circle lies at the x-axis
Let r be the radius of the circle
Then, the equation of a circle with centre at (r,0) is
-(i)
Now, differentiate w.r.t x
-(ii)
Put equation (ii) in equation (i)
Therefore, the required equation is