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JEE Mains · Maths · STD 11 - 7. binomial theoram

माना \(n \geq 5\) पूर्णांक है। यदि \(9^{ n }-8 n -1=64 \alpha\) तथा \(6^{ n }-5 n -1=25 \beta\) है, तो \(\alpha-\beta\) बराबर है

  1. A \(1+{ }^{n} C_{2}(8-5)+{ }^{n} C_{3}\left(8^{2}-5^{2}\right)+\ldots+{ }^{n} C_{n}\left(8^{n-1}-5^{n-1}\right)\)
  2. B \(1+{ }^{n} C_{3}(8-5)+{ }^{n} C_{4}\left(8^{2}-5^{2}\right)+\ldots+{ }^{n} C_{n}\left(8^{n-2}-5^{n-2}\right)\)
  3. C \({ }^{n} C_{3}(8-5)+{ }^{n} C_{4}\left(8^{2}-5^{2}\right)+\ldots+{ }^{n} C_{n}\left(8^{n-2}-5^{n-2}\right)\)
  4. D \({ }^{n} C_{4}(8-5)+{ }^{n} C_{5}\left(8^{2}-5^{2}\right)+\ldots+{ }^{n} C_{n}\left(8^{n-3}-5^{n-3}\right)\)
Verified Solution

Answer & Solution

Correct Answer

(C) \({ }^{n} C_{3}(8-5)+{ }^{n} C_{4}\left(8^{2}-5^{2}\right)+\ldots+{ }^{n} C_{n}\left(8^{n-2}-5^{n-2}\right)\)

Step-by-step Solution

Detailed explanation

\(\alpha=\frac{(1+8)^{ n }-8 n -1}{64}={ }^{ n } C _{2}+{ }^{ n } C _{3} 8+{ }^{ n } C _{4} 8^{2}+\ldots\) \(\beta={ }^{n} C_{2}+{ }^{n} C_{3} 5+{ }^{n} C_{4} 5^{2}+\ldots\) option \((3)\) will be the answer.
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