Ampop circuit, analyse this circuit

[cookas]

Hi,
Can anyone help me to analyse this circuit? I want to determine Vout/Vi but the Rc is confusing me.
I need to find the common mode voltage and the differencial mode voltage.

Thanks

 

[Fred Gomes]

hello..
it´s analizes the diferencial between terminal + and - , and this diferece is amplified... for example, if you have 5v in terminal + and 0 v in terminal -, you have one aplification, but if you have 0v in terminal + and 5v in - , already you get neither amplification.. is simple..