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COMEDK2017MathematicsBinomial Theorem

Given, the positive integers r>1, n>2 and the coefficients of (3 r) th and (r+2) th terms in the expansion of (1+x)^ 2 n are equal, then n=

Options

  1. A2 r
  2. B2 r-1
  3. C2 r+1
  4. D3 r

Correct answer

A. 2 r

Step-by-step solution

( array c 2 n 3 r-1 array )= ( array c 2 n r+1 array ) array c n x = n y x+y=n or n-x=y array 2 n=3 r-1+r+1 n=2 r

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