[![enter image description here](https://i.stack.imgur.com/6w0ZV.png)](https://i.stack.imgur.com/6w0ZV.png)

[![enter image description here](https://i.stack.imgur.com/jBsoM.jpg)](https://i.stack.imgur.com/jBsoM.jpg)

I have attached my attempt and the solution provided by my instructor. I am confused on 2 things

1. what it means by "the circuit is in quiescent state" ?
2. why is he getting sqrt(8) in the current equation ?

Edit1: I have also attempted the same problem using Laplace

[![enter image description here](https://i.stack.imgur.com/ApULG.jpg)](https://i.stack.imgur.com/ApULG.jpg)