Let $f:\mathbb{R}\to\mathbb{R}$ be defined by $f(x)=\dfrac{x}{(1+2x^{4})^{1/4}}$, and $g(x)=f(f(f(f(x))))$. Then $18\displaystyle\int_{0}^{\sqrt{2\sqrt{5}}} x^{2}g(x),dx$ is equal to: