Chapter 16, Problem 92AP

Show that the wave equation in one dimension

   $\frac{{\partial }^{2}f}{\partial x^2}=\frac{1}{v^2}\frac{{\partial }^{2}f}{\partial t^2}$

Is satisfied by any doubly differentiable function of either the form f(x — vt) or f(x + vt).