Dear All

How do I solve the followinh set of non-linear equations for the unknowns as given below:
    

    Zth1=R1(1-e^(-t1/tau1))+R2(1-e^(-t1/tau2))+R3(1-e^(-t1/tau3))+R4(1-e^(-t1/tau4))+R5(1-e^(-t1/tau5))+R6(1-e^(-t1/tau6))

    Zth2=R1(1-e^(-t2/tau1))+R2(1-e^(-t2/tau2))+R3(1-e^(-t2/tau3))+R4(1-e^(-t2/tau4))+R5(1-e^(-t2/tau5))+R6(1-e^(-t2/tau6))

    Zth3=R1(1-e^(-t3/tau1...