# Equation of the circle with centre on the $y$-axis and passing through the origin and the point $(2,3)$ is
$\begin{array}{1 1}x^2+y^2+13y=0\\3x^2+3y^2+13x+3=0\\6x^2+6y^2-13x=0\\x^2+y^2+13x+3=0\end{array}$