http://en.wikipedia.org/wiki/Taylor_series
http://www.wolframalpha.com/input/?i=taylor%28%281-z%29^%28-1%2F2%29%2Cz%29
notice that the series is not the same. I think the wolfram version is wrong. how could i report it?
oh, sorry. didn't notice that. i worked in the wrong way. thank you.
What exactly is not the same? If you mean the expansion around 0, it's the same as on Wikipedia, since we are taking x = -z.