✓ Mathematica : cpu = 0.025259 (sec), leaf count = 32
DSolve[Derivative[2][y][x] == -(((6*b + 2*a*x)*y[x])/(x^2*(b + a*x))) + (2*(2*b + a*x)*Derivative[1][y][x])/(x*(b + a*x)),y[x],x]
✓ Maple : cpu = 0.033 (sec), leaf count = 20
dsolve(diff(diff(y(x),x),x) = 2/x*(a*x+2*b)/(a*x+b)*diff(y(x),x)-(2*a*x+6*b)/(a*x+b)/x^2*y(x),y(x))