I have the series (cosx)^-1/2 (so it's square-rooted and on the bottom)(adsbygoogle = window.adsbygoogle || []).push({});

And I need to get the first few terms. My idea has been to do this: [1 + (cosx - 1)]^-1/2

But I have no idea how to take the binomial expansion of that. Do I:

Take the BE first, substituting "cosx - 1" as just X or something, then after I get the first few terms of that, substitute in the series for "cosx - 1" back into X and adding everything up? The only reason I haven't tried this yet is because it seems like this would take an infinite amount of work... :yuck:

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# Expanding a series

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