Can you explain the whole solution?

[alexnder4444]

please explain me the whole solution

 

[berkeman]

No. We do not give answers here on the PF. We can act as tutors if you show us the relevant equations and show us your work on the problem. That is why we have the Homework Help Template that you deleted when you posted this thread. In the future, please use the Template to be sure that you will get the best quality help from us.

Now, show us the relevant equations and your attempt at a solution.