nice thank you very much. I will look at this more closely this evening. I just recently took Modern physics in the spring for fun. I'm more or less a perpetual student. I got an undergrad degree in accounting in 1999, an MS in telecommunications in 2002 and I've been taking math and physics...
The book is the Serway / Moses / Moyer Modern Physics 3rd edition. He got back to me with the following:
"The Lorenz-Transformation is based on c2t2-x2 -y2 -z2 =c2t'2-x'2 -y'2 -z'2 (A) where (x,y,z,t) and (x',y',z',t') are coordinates of a light signal (photon) with speeds ux = ux' = c in...
1. The 2nd line on the 3rd page of your notes, you have x=ct and
x'=ct', thus ux=dx/dt and ux'= dx'/dt' =c according to Einstein's
assumptiuon.
2. But near the end of the last page, you wrote dx'/dt' = (ux
-v)/(1-vux/c2) . Compare with 1. This equation can be valid only for ux=c
and...