find the 13th term in the expansion of(9x-1/3rootx)^18,x is not equal to 0.

Asked by  | 8th Nov, 2012, 12:16: PM

Expert Answer:

In case of binomial expansion of (a+b)n, it is written as
nC0an+nC1an-1b+......+nCnbn
So, for the given expression, the 13th term will be 18C13(9x)13/35x5/2
18!913x13/13!5!923x5/2 = (14)(2)(17)(6)(9)11(x)21/2
=2856(9)11(x)21/2
 
This is the 13th term

Answered by  | 8th Nov, 2012, 04:26: PM

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