Relativity Question: Solving Equation 3.50

[S.P.P]

Hi all,

I'm trying to teach myself relativity using Sean Carroll's lecture notes. Although this Isn't a homework question I thought this part of the forum was the best place to ask.

On page 76 of http://arxiv.org/pdf/gr-qc/9712019, how have they got the first equation in (3.50) from plugging (3.49) into (3.48). I can't understand where some of the terms have gone? I must be missing something. Can someone explain how this has been achieved.

Thanks in advance!

 

[George Jones]

When you plug (3.49) into (3.48), neglect all terms that have two or deltas.