Hi, I have done a, b but i need help on the rest please

3. The equation for the instantaneous voltage across a discharging capacitor is given by v = Voe , where Vo is the initial voltage and r is the time constant of the circuit. The tasks are to: a) Draw a graph of voltage against time for Vo = 12V and r = 2s, between t = 0s and t = 10s. b) Calculate the gradient at t = 2s and t = 4s. c) Differentiate v = 12e ? and calculate the value of dt at t = 2s and t = 4s. d) Compare your answers for part b and part c. e) Calculate the second derivative of the instantaneous voltage dt