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Summation and Binomial Coefficients

Calculate k=1n(nk)3k \sum_{k=1}^{n} \binom{n}{k} 3^k
Original post by bijesh12
Calculate k=1n(nk)3k \sum_{k=1}^{n} \binom{n}{k} 3^k


Compare it with the standard binomial expansion - see http://en.wikipedia.org/wiki/Binomial_theorem

Section on "Statement of the theorem", expansion of (x+y)n(x+y)^n.

What are x,y here?
Reply 2
Original post by bijesh12
Calculate k=1n(nk)3k \sum_{k=1}^{n} \binom{n}{k} 3^k


Binomial.jpg
(edited 10 years ago)

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