C2 Geometric series / Binomial expansion question. Watch

Louisb19
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Hi.

In my revision i have found this question in a Geometric series exercise sheet. Any help would be appreciated.

6) Write down the first 4 terms in ascending powers of x in the binomial expansion of

a) (2+x)^10
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Parallex
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you're just being asked to expand it?
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Louisb19
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I was thinking that the first 4 terms in ascending powers of x would be (in reverse order):

10C0 X 2^10 X x^0

10C1 X 2^9 X x^1

10C2 X 2^8 X x^2

10C3 X 2^7 X x^3

Does this sound right? The thing that gets me about this question is the wording and the fact that it is in a Geo Series sheet.
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ztibor
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(Original post by Louisb19)
Hi.

In my revision i have found this question in a Geometric series exercise sheet. Any help would be appreciated.

6) Write down the first 4 terms in ascending powers of x in the binomial expansion of

a) (2+x)^10
Write down the binomial expansion in reverse order starting from the 4. term.

( \displaystyle \binom{10}{3} 2^7\cdot x^3 + ....)
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Louisb19
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(Original post by ztibor)
Write down the binomial expansion in reverse order starting from the 4. term.

( \displaystyle \binom{10}{3} 2^7\cdot x^3 + ....)
Why does 2 not have any power? I thought the formula was: nC0 X a^n X b^0 + nC1 X a^n-1 X b^1 ... nCn X a^0 X b^n

Did I do something wrong?

EDIT: Oh i see you have now changed the power . Thanks for the help!
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TenOfThem
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(Original post by Louisb19)
I was thinking that the first 4 terms in ascending powers of x would be (in reverse order):

10C0 X 2^10 X x^0

10C1 X 2^9 X x^1

10C2 X 2^8 X x^2

10C3 X 2^7 X x^3

Does this sound right? The thing that gets me about this question is the wording and the fact that it is in a Geo Series sheet.
This is correct ... Now idea why it is on that sheet
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