Please with circuit ASAP, thanks first

[tinhnho]

hi everyone

can someone helps me out this proplem? just tell me which to start, i'm totally dont undestand this proplem

here is the link

www.viethost4u.com/EE.GIF

sorry about the picture too big (79kb) ,i can't upload up here

[tinhnho]

Herer what i did :
Case 1
i(t)= (v0/R)*e^(t/R*C)
i(0)= vo/R
i(infinity)= 0

Case 2
v(t)=v0*e^(-t/RC)
v(0+)= v(0)
v(infinity)= 0

Case 3
i(t)= -C*(dv/dt)= -C* d(v0*e^(t/R*C))/dt
i(0)= -C*d(v0)/dt
i(infinity)= 0

Case 4
v(t)=v0*e^(-t/RC)
v(0+)= v(0)
v(infinity)= 0

are those right ?