\[1)\ f(x) = \frac{1}{4x^{2}} - \sqrt{x};\ \ x_{0} = 1:\]
\[f^{'}(x) = \frac{1}{4}\left( x^{- 2} \right)^{'} - \left( x^{\frac{1}{2}} \right)^{'} =\]
\[= \frac{- 2x^{- 3}}{4} - \frac{1}{2}x^{- \frac{1}{2}};\]
\[tg\ a = f^{'}(1) = \frac{- 2 \bullet 1^{- 3}}{4} - \frac{1}{2} \bullet 1^{- \frac{1}{2}} =\]
\[= - \frac{1}{2} - \frac{1}{2} = - 1;\]
\[a = arctg\ ( - 1) =\]
\[= - arctg\ 1 = - \frac{\pi}{4}.\]
\[Ответ:\ \ a = - \frac{\pi}{4}.\]
\[2)\ f(x) = 2x\sqrt{x},\ \text{\ \ }x_{0} = \frac{1}{3};\]
\[f^{'}(x) = 2\left( x^{\frac{3}{2}} \right)^{'} =\]
\[= 2 \bullet \frac{3}{2} \bullet x^{\frac{1}{2}} = 3\sqrt{x};\]
\[tg\ a = f^{'}\left( \frac{1}{3} \right) = 3 \bullet \sqrt{\frac{1}{3}} =\]
\[= \sqrt{\frac{9}{3}} = \sqrt{3};\]
\[a = arctg\ \sqrt{3} = \frac{\pi}{3}.\]
\[Ответ:\ \ a = \frac{\pi}{3}.\]