http://imgur.com/hAzf2zP So I found the circuit is series, w0 and a0 equal 20 so it is critically dampened. For V(inf) I used current divider to get the equation (.1 A *120 ohm)/40 ohm = .3 A. Then I used ohms law to find v(t) = .3*120 = 36 V.
I then wrote down the circuit at t<0, t>0, and...