\[h = 24t - 5t^{2}\]
\[\ m = - \frac{24}{10} = - 2,4;\]
\[n = 24 \cdot ( - 2,4) - 5 \cdot 5,76 =\]
\[= 57,6 - 28,8 = 28,8.\]
\[24t - 5t^{2} = 0\]
\[t(24 - 5t) = 0\]
\[t = 0;\ \ \ 5t = 24\]
\[\ \ \ \ \ \ \ \ \ \ \ \ \ \ \ t = 4,8.\]
\[поднимался\ при\ 0 \leq t \leq 2,4;\]
\[опускался\ при\ \ 2,4 < t \leq 4,8.\]