Find f''(x) if $\displaystyle f(x)=\frac{x^2}{\sqrt{x^2+4}}$

so which method would be easier to solve for? The quotient rule or should I bring $\displaystyle \sqrt{x^2+4}$ to the numerator as $\displaystyle (x^2+4)^-^\frac{1}{2}$ and use the product rule and chain rule?