$$\left. \begin{array} { l } { \sqrt { 10 } x ^ { 2 } - 8 x + 4 \sqrt { 15 } } \\ { \quad } x _ { 4 } \sqrt { x } = 12 } \end{array} \right.$$
$y=4\sqrt{15}-\frac{1152}{x_{4}^{2}}+\frac{20736\sqrt{10}}{x_{4}^{4}}$
