Consider an infinite string stretched taut on the x-axis from oo to co. Let the string be drawn aside into a curve y = f(x) and released, and assume that its subsequent motion is described by the wave equation (I) together with the initial conditions: gt lt=0o = 0, u(x,0) = f(x) Use (*) to show that the string's displacement is given by d'Alembert's formula, u(x, t) = %U'(x + at) + f(x at)]