For reference, this is the paragraph in Wikipedia I'm struggling with.
https://en.wikipedia.org/wiki/Autoregressive_model
I do understand the simpler proof for under which conditions an AR(1) process is stationary, however I do not understand
a.) how to make the connection between the condition for AR(1) to be stationary () and the generalized condition for the root |z| > 1.
b.) How to show that |z|>1 must hold for AR(p) to be stationary and the "intuition" behind the second condition (if there is any)
Any help is greatly appreciated. Thank you all in advance!