Find the differential equation of system of cocentric circles with centre (1,2)

Options

A. `(x-2)+(y-1)(dy)/(dx)=0`
B. `(x-1)+(y-2)+(y-2)(dy)/(dx)=0`
C. `(x+1)(dy)/(dx)+(y-2)=0`
D. `(x+2)(dy)/(dx)+(y-1)=0`

Answer

B

Explanation

Given that centre of circle is (1,2)
let radius of circle is a.
`therefore(x-1)^(2)+(y-2)^(2)=a^(2)`
`implies2(x-1)+2(y-2)(dy)/(dx)=0`
`implies(x-1)+(y-2)(dy)/(dx)=0`