$\begin{aligned} & y=\frac{(\sqrt{x}+1)\left(x^2-\sqrt{x}\right)}{x \sqrt{x}+x+\sqrt{x}}+\frac{1}{15}\left(3 \cos ^2 x-5\right) \cos ^3 x y=\frac{(\sqrt{x}+1)(\sqrt{x})\left((\sqrt{x})^3-1\right)}{(\sqrt{x})\left((\sqrt{x})^2+(\sqrt{x})+1\right)}+\frac{1}{5} \cos ^5 x-\frac{1}{3} \cos ^3 x \mathrm{y}=(\sqrt{\mathrm{x}}+1)(\sqrt{\mathrm{x}}- \\ & 1)+\frac{1}{5} \cos ^5 \mathrm{x}-\frac{1}{3} \cos ^3 \mathrm{xy}^{\prime}=1-\cos ^4 \mathrm{x} \cdot(\sin \mathrm{x})+\cos ^2 \mathrm{x}(\sin \mathrm{x}) \\ & y^{\prime}\left(\frac{\pi}{6}\right)=1-\frac{9}{16} \times \frac{1}{2}+\frac{3}{4} \times \frac{1}{2} \\ & =\frac{32-9+12}{32}=\frac{35}{32} \\ & =96 y^{\prime}\left(\frac{\pi}{6}\right)=105\end{aligned}$