1. The problem statement, all variables and given/known data The position function of a particle is given by r(t) = <2t, 3, -2t+1> where t is the time in seconds. When is the speed a minimum? What is the minimum speed? 2. Relevant equations v(t) = r'(t) 3. The attempt at a solution The derivative of r'(t) = 2 + 0 + (-2) = 0. The t is cancelled out so how are we supposed to find t and the minimum speed? I am so confused. Help please?