Retruning to equilibrium - dynamical system

["Gianni"]

Hi,
    I'm studying the dynamical system at very low level and I hope someone 
may help me.
I've got this problem:
Given the system described by the following linear evolution Vn+1 = AVn, in 
which A:

|1/2  t  |
|1   1/3|

find the "t" values for which the system return to the equilibrium, and the 
way it comes back to the equilibrium.

Thank you,
 G.