Numerical Analysis problem

[hannah.ek94]

I'm not really sure how to approach this problem so i really appreciate if someone can help!

Ex/let Xn=(1/2)*(Xn-2 + (2/Xn-1), n≥1

i) How can i show that the sequence converges to √2
ii) how can i show that the order of converges is 2

Thanks for you helps!!