1. The problem statement, all variables and given/known data I have a RLC circuit in series. I am trying to find the current i(t) passing through this RCL circuit. When solving the RCL circuit, it happened to be critically damped. And simplified i ended up with: i(t) = A2te-20t Where i need to find what is the cosntant A2 2. Relevant equations R = 100Ohm L = 2.5H C = 1mF i(0) = 0A vC(0) = 24V vL = L di/dt vR = iR di/dt = -20A2te-20t 3. The attempt at a solution I apply KVL to the closed RCL loop and get: vC + vL + vR = 0 vC(0) + L di(0)/dt + i(0)R = 0 24V + 2.5H di(0)/dt + 0 = 0 di(0)/dt = -24V/2.5H = -9.4A But di/dt is also -20A2te-20t so di(0)/dt = -9.4 = -20A2(0)e-20(0) -9.4 = 0 which is fallacy but according to the book: A2 = -9.4 so, i(t) = -9.4te-20t Where did i go wrong?