I'm having difficulties in using least squares curve fitting. I have a differential equation which explains the behavior of a simple circuit. I don't know what the values of the circuit elements are, but I've collected data that shows the circuit's behavior. Here is the equation I am trying to fit this data to:

(di/dt)*C*R1*R2 + i*(R1+R2) = (dv/dt)*C*R1 + v

where di/dt is the derivative of current (i) with respect to time.
dv/dt is the derivative of voltage (v) with respect to time.
I have the waveforms and datapoints for both v and i with respect to time. I don't know C (capacitance) R1 (resistor 1) and R2 (resistor 2). I was hoping to use least squares to fit the v and i datapoints to the above equation, but I don't know how to resolve the issue with the third variable, time t. Any help would be appreciated.