2. Consider and elastic string of length 10 whose ends are held fixed. The string is set in motion with no initial velocity from an initial position $u(x, 0) = f(x)$, where \\
$f(x) = \begin{cases} x/5 & \text{if } 0 \le x \le 5, \\ (10 - x)/5 & \text{if } 5 < x \le 10. \end{cases}$ \\
Find $u(x, t)$ (Assume $a = 1$.)