Principle Of Mathematical Induction Question 61

Question: $ \frac{(2n)!}{2^{2n}{{(n!)}^{2}}}is\le $

Options:

A) $ \frac{1}{3n+1} $

B) $ \frac{1}{{{(3n+1)}^{1/2}}} $

C) $ \frac{1}{{{(3n+1)}^{2}}} $

D) $ \frac{1}{{{(3n+1)}^{1/2}}} $

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Answer:

Correct Answer: B

Solution:

  • [b] By setting $ n=1, $ we get $ \frac{2n!}{2^{2n}.{{(n!)}^{2}}} $ as $ \frac{2}{2^{2}.{{(1)}^{2}}}=\frac{2}{4}=\frac{1}{2}. $
    Second alternative gives $ \frac{1}{2} $ . Upon setting $ n=2,\frac{2n!}{2^{2n}.{{(n)}^{2}}} $ becomes $ \frac{3}{8} $ , second alternative Becomes $ \frac{1}{\sqrt{7}} $ which is greater than $ \frac{3}{8}. $