This isn't homework, but it feels like it...it's from the Dorf & Svoboda Introduction to Electric Circuits, 6th ed. on p 298, if you happen to have that. I'm following the derivation of the formula for capacitor voltage for an RC circuit with a single resistor and single cap, or the current in the simple inductor circuit. Arriving at the general form of the differential equation, with time constant T: dx(t)/dt + x(t)/T = K rewritten: dx/dt = (KT - x)/T now, in the next step, the authors separate the variables and multiply each side by -1, yielding: dx/(x - KT) = -dt/T and go on to integrate both sides and arrive at: ln(x - KT) = -t/T + D D being the constant of integration. Raising e to both sides you get: x(t) = KT + Ae-t/T where A is eD, and you can go on using initial conditions to solve for the constant. I can't get the same result when I don't multiply both sides by -1 when separating variables before solving the equation. My steps are as follows: dx/dt = (KT - x)/T dx/(KT - x) = dt/T having not multiplied by -1 ln(KT - x) = t/T + D KT - x = Aet/T x(t) = KT - Aet/T This doesn't appear to be the same solution, as en is not equal to -e-n. Can somebody please help me figure out what I've missed? Oh, and hello everybody. I'm a junior engineer but work in a field that barely ever touches on a lot of what I learned in school...I've decided to start studying again to make sure I retain the fundamentals, especially if I do switch into a hardware design position. Thank you.