1. The problem statement, all variables and given/known data Hi, If there is a series combination of a resistor and an initially charged capacitor, I know that the decay of the voltage is given by the equation v(t) = Ae^(-t/RC) where V(0) = A = V0. But i am unsure of how to get to this equations. 2. Relevant equations If I assume Ir = current flowing through resistor and Ic = current flowing through Capacitor and assume there both flowing out of the node. 3. The attempt at a solution Then: Ic + Ir = 0 C(dv/dt) + V/R = 0 V/R = -C(dv/dt) 1/V(dv) = -1/RCdt integrate both sides ln v = -t/RC + A A= integration constant Here is where i cant go no more I saw somewhere they got: ln v = -t/RC + ln A, from there I know how to get the solution but how to arrive at ln A?, can we just do this automatically because it is a constant to make life easier or is there some logic behind it?