Binomial Theorem 1 Question 20

22.

In the binomial expansion of (ab)n,n5 the sum of the 5th and 6th terms is zero. Then, a/b equals

(a) n56

(b) n45

(c) 5n4

(d) 6n5

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Answer:

Correct Answer: 22. (b)

Solution:

  1. Given, T5+T6=0

nC4an4b4nC5an5b5=0

nC4an4b4=nC5an5b5ab=nC5nC4=n45



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