Q. The differential equation of system of concentric circles with centre (1,2) is
A) $(x - 2) + (y - 1)\frac{dy}{dx} = 0$
B) $(x - 1) + (y - 2)\ \frac{dy}{dx} = 0$
C) $(x + 1)\frac{dy}{dx} + (y - 2) = 0$
D) $(x + 2)\frac{dy}{dx} + (y - 1) = 0$
Explanation
(b)
Given that centre of circle is (1, 2).
Let radius of circle is$a$.
$\therefore$ $(x - 1)^{2} + (y - 2)^{2} = a^{2}$
$\Rightarrow$ $2(x - 1) + 2(y - 2)\frac{dy}{dx} = 0$
$\Rightarrow$ $(x - 1) + (y - 2)\frac{dy}{dx} = 0$
Reviewed by Dr. Abubacker
Physics Educator & NEET/JEE Specialist
Ph.D. in Physics with 19+ years of teaching experience.