The interval in which x must lie so that the greatest term in the expression of (1+x)2n has the greatest coefficient, is
Here the greatest coefficient is 2nCn
∴ 2nCnxn>2nCn+1xn−1⇒x>nn+1
and 2nCnxn>2nCn−1xn+1⇒x<n+1n
Hence the required interval is (nn+1,n+1n).