If $\mathrm{L}=\underset{\mathrm{x}\to \mathrm{\infty }}{lim} \left(\sqrt[3]{{\mathrm{x}}^3+2{\mathrm{x}}^2}-\sqrt{{\mathrm{x}}^2+\mathrm{x}}\right)$ then the value of 3/L is ______ .

$\begin{array}{l}\underset{\mathrm{x}\to \mathrm{\infty }}{lim} \left(\sqrt[3]{{\mathrm{x}}^3+2{\mathrm{x}}^2}-\sqrt{{\mathrm{x}}^2+\mathrm{x}}\right)\\ =\underset{\mathrm{x}\to \mathrm{\infty }}{lim} \mathrm{x}\left[{\left(1+\frac{2}{\mathrm{x}}\right)}^3-{\left(1+\frac{1}{\mathrm{x}}\right)}^{\frac{1}{2}}\right]\\ =\underset{\mathrm{x}\to \mathrm{\infty }}{lim} \mathrm{x}\left[\left(1+\frac{1}{3}\cdot \frac{2}{\mathrm{x}}+\dots \right)-\left(1+\frac{1}{2}\cdot \frac{1}{\mathrm{x}}+\dots \right)\right]\\ =\underset{\mathrm{x}\to \mathrm{\infty }}{lim} \mathrm{x}\left(\frac{2}{3\mathrm{x}}-\frac{1}{2\mathrm{x}}\right)\\ =\frac{1}{6}\end{array}$