1. The problem statement, all variables and given/known data Consider the electrical circuit shown: http://imageshack.us/a/img525/8163/p1circuit.png [Broken] Let the state variables be x1(t)=Vc(t), x2(t)=iL(t), and x3(t)=Vc(t); output is Vo(t). Write the state-space equations in matrix form and find the transfer function, T(s)=Vo(s)/Vi(s). 2. Relevant equations KCL and KVL 3. The attempt at a solution State Variables: x1(t)=Vc(t) x2(t)=iL(t) x3(t)=Vo(t) Outputs: Vo(t) Inputs Vi(t) Differential Equations for State Variables: X1'=dV1/dt=i2 X2'=di4/dt=V2 X3'=dVo/dt=i5 Now this is the part that I am stuck at. I know that I have to solve for X1', X2', and X3' in terms of the state variables and inputs only. However, I can't seem to reduce the equations enough to get it into this format. Basically, I am trying to solve for i2, i5, and V2 in terms of i4, V1, Vo, and Vi only (the state variables and inputs). Once I have these equations, I can easily put them into matrix form and solve using MATLAB. I solved a problem earlier that was exactly the same, only the first capacitor was replaced with an inductor. So, I think it is the capacitor that is giving me problems. A few equations that I found: Vi=i1+i3+i5+Vo i3=i1-i2 i5=i3-i4 V1=Vi-i1 V2=V1-i3 Vo=V2-i5 Thanks for the help! Edit: I looked over the problem again, and it seems that I can't solve for i3 without it containing a V2 or an i2. Is there any way to solve for i3 with a combination of only i4, V1, Vo, and Vi? Once I find this, I will be able to solve the problem.