Chap 5 section 5.1 : random walk

[@onisuzume98]

thank you ! good luck with your new job

[@mbaye501]

Thank you

[@markovwallenstein9357]

how to prove proposition 4.1.1 in Chapter 4 of 'Stochastic Process' by Sheldon M. Ross. the proof given by the author doesn't go into detail. I can't comprehend.