How einstein proved equation about speed

[Hepic]

How einstein proved that equation: U=(V1+V2)/(1+(V1*V2)/c^2) ?
Thanks !!!

 

[phinds]

How einstein proved that equation: U=(V1+V2)/(1+(V1*V2)/c^2) ?
Thanks !!!

http://hyperphysics.phy-astr.gsu.edu/hbase/relativ/veltran.html#c1

 

[Hepic]

As I see Lorentz helped a lot to this equations.
How lorenz proved them?

 

[Vanadium 50]

What did you not understand about the answer you got?