$4.(20)$ In the circuit shown, the switch has been closed for a long time. It opens at time $\backslash ($ t$=0\backslash ).$ Find an expression for current $\backslash ($ i$\_\{0\}($t$)\backslash )$ for time $\backslash ($ t$>0\backslash ).$ Note the location of current $\backslash ($ i$\_\{0\}\backslash )$ in the diagram. Show your work and confirm your calculations by using two methods: preferably the differential equation method and the step$-$by$-$step method $($or any other method$($s$)$ you learn through self$-$study$).$