\[\boxed{\mathbf{1029}\mathbf{.}}\]
\[\ y = C_{1} \bullet \cos\text{ωx} + C_{2} \bullet \sin\text{ωx}\]
\[y^{'}(x) =\]
\[= C_{1} \bullet \left( \cos\text{ωx} \right)^{'} + C_{2} \bullet \left( \sin\text{ωx} \right)^{'};\]
\[Получаем:\ \]
\[y^{''} = - \omega^{2} \bullet y\]
\[y^{''} + \omega^{2} \bullet y = 0.\]
\[Что\ и\ требовалось\ доказать.\]