Binomial expansion question

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#1
Just a quick question why is x valid for modulus of 1/2 and not 1/3?

Part b(ii)
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#2
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2 years ago
#3
(Original post by Svesh)
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Expansion of is valid for all but the expansion of isn't.

Overall, the range of validity is where both of these expansions are valid. So if the first one is valid at all times, and the second one isn't, then clearly the problem reduces to finding out when the second expansion is valid.
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#4
(Original post by RDKGames)

Expansion of is valid for all but the expansion of isn't.

Overall, the range of validity is where both of these expansions are valid. So if the first one is valid at all times, and the second one isn't, then clearly the problem reduces to finding out when the second expansion is valid.
Ah ok that makes sense but why is all x valid for (1+3x)^2
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2 years ago
#5
(Original post by Svesh)
Ah ok that makes sense but why is all x valid for (1+3x)^2
Is it not clear? which obviously holds and converges for any value you put in. It doesn't "break down" for certain like the infinite expansion.
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#6
(Original post by RDKGames)
Is it not clear? which obviously holds and converges for any value you put in. It doesn't "break down" for certain like the infinite expansion.
oh yh lol completely forgot. Just going back over c4 now and forgotten some knowledge. Thanks!!
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