The differential equation of the family of curves v=A/r+B where A and B are arbitrary constants is

Dear palllavi

 v=A/r+B

differentiate

dv/dr =-A/r²

r²dv/dr =-A

again differentiate

r²d²v/dr² + 2rdv/dr =0

rd²v/dr² + 2dv/dr =0

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