The displacement, sss millimetres, of a robotic arm at time ttt seconds is given by the equation
s=(0.35t−4.2)e0.4t s = (0.35t - 4.2) e^{0.4t} s=(0.35t−4.2)e0.4tDetermine, using calculus, the exact value of ttt for which the displacement has a stationary point.