In which region the curve $y^{2}(a+x)=x^{2}(3a-x)$ does not lie?

Question

\[\begin{array}{1 1}(1)\;x>0&(2)\;0< x < 3a \\(3)\;x<-a\; \text{and}\; x>3a & (4)-a \end{array} \]