I need help understanding something from a RL circuit problem.
At a steady state (DC conditions), the inductor will have no resistance, and will act like a short. Since current wants to take the path of least resistance, all the current will flow through the inductor (instead of the 6 ohm resistor). 

For t&lt;0, since the inductor has 0-ohms of resistance, it's short circuiting the current path through the 6 ohm resistor. 

For t>0, once the switch closes, all the current from the voltage source will take the path of least resistance through the closed switch leg (as opposed to the other leg that it is in parallel with).

Sorry if I went very basic with this explanation. Hope it helps :)