what is this?

[bogdanfirst]

can anybody tell me whar this formulas are for ?
i dont understand a thing ....
https://www.rfcafe.com/references/electrical/s-h-y-z.htm

 

[kinjalgp]

These are ABCD network analysis equations. Any electrical network can be analysed using 4 different parameters
1) Z parameters (impedance parameters)
2) Y parameters (admnittance parameters)
3) H parameters (hybrid parameters)
4) ABCD parameters

This analysis is done to find out the i/p and o/p impedances and their inter-relationships. Also these are used to simplify and complex network into simple 2-port network.