Series Solutions · Easy problem

A point $x_0$ is a singular point of $P(x)y'' + Q(x)y' + R(x)y = 0$ (polynomial coefficients with no common factor) when $P(x_0) = 0$. Find the sum of the singular points of $(x^2 - 5x + 6)\,y'' + x\,y' + y = 0$.