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

Answer

d

Explanation

Given that centre of circle is (1,2)
Let radius of circle is a.
` :. (x -1)^(2) +(y-2)^(2) = a^(2)`
` rArr 2(x-1) +2 (y -2) (dy)/(dx) = 0 ` [ differentiating ]
` (x-1) + (y -2) (dy)/(dx) = 0`