Find the differential equation of family of all straight lines passing through the origin .

Find the differential equation of the family of lines passing through the origin.

Find the differential equation of the family of all circles which pass through the origin and whose centre lie on y-axis.

Obtain the differential equation of the family of circles passing through the point (a,0) and (-a,0).

Obtain the differential equation of the family of circles passing through the point (a,0) and (-a,0).

Find the differential equation of all the circles which pass through the origin and whose centres lie on y-axis.

Find the differential equation of all the circles which pass thorough the origin and whose centres lie on x-axis.

Find the differential equation of all straight lines touching the circle x^2+y^2=a^2

Find the equation of a line parallel to x-axis and passing through the origin.

Find the equation of a line parallel to x-axis and passing through the origin.

Find the equation of line parallel to y-axis and passing through the origin.