Determine which of the following functions describe travelling waves, by plugging them into the wave equation and seeing if they satisfy it and under what conditions. If a function describes a wave, draw the profile and find the speed and direction of motion. a) y (x,1) = Ae-(x-b) b) y (x,t) = A cos(a x- +b't?) c) w(x,t) = A sin(a x' + b't' - 2abxt)