The switch has been closed for a long time and is opened at t$=0.$ If R$=5$ ohms,

a$.$ Write and expression for the transient voltage response Vtr$($t$)$ for t$>0$ with two unknown constants.

b$.$ What is the steady$-$state value of the voltage v$?$

c$.$ Find v$($t$)$ for t$>0,$ with all unknown constants evaluated using appropriate initial conditions.