\[\boxed{\mathbf{826\ (826).\ }Еуроки\ - \ ДЗ\ без\ мороки}\]
\[y_{1} = 64;\ \ q = - \frac{1}{2}\]
\[1)\ y_{3} = y_{1} \cdot q² = 64 \cdot \left( - \frac{1}{2} \right)^{2} =\]
\[= \frac{64}{4} = 16;\]
\[2)\ y_{6} = y_{1} \cdot q^{5} = 64 \cdot \left( - \frac{1}{2} \right)^{5} =\]
\[= - \frac{64}{32} = - 2;\ \]
\[3)\ y_{10} = y_{1} \cdot q^{9} = 64 \cdot \left( - \frac{1}{2} \right)^{9} =\]
\[= - \frac{2^{6}}{2^{9}} = - \frac{1}{2^{3}} = - \frac{1}{8}.\]