1. An electron moving along the x-axis has a position given by x=16*te^-t m, where t is in seconds. How far is the electron from the origin when it momentarily stops? 2. Relevant equations uv=u'v+uv' 3. The attempt at a solution x'=e^-t - t*e^-t e^-t - t*e^-t = 0 -te^-t = -e^-t t = 1?