$\mathop {\lim }\limits_{x \to {0^ + }} \left( {\frac{{\tan \left( {5{x^{1/3}}} \right)}}{{5{x^{1/3}}}}} \right) \cdot \left( {\frac{{{{(3\sqrt x )}^2}}}{{{{\left( {{{\tan }^{ - 1}}3\sqrt x } \right)}^2}}}} \right)\left( {\frac{{\ell \left( {1 + 3{x^2}} \right)}}{{3{x^2}}}} \right)\left( {\frac{{5{x^{4/3}}}}{{{e^{5{x^{\frac{4}{3}}}}} - 1}}} \right) \times \frac{{5{x^{1/3}} \cdot 3{x^2}}}{{5{x^{4/3}} \cdot 9x}}$ $ = \frac{1}{3}$