1ans is (b)( n/{n+1} , {n+1}/n )
The interval in which x(>0) must lie so that the greatest term in the expansion of (1+x)2n has the greatest coefficient is
(a)(n-1/n,n/n-1)
(b)(n/n+1,n+1/n)
(c)(n/n+2,n+2/n)
(d)None of these.
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4 Answers
1u can take 2 approach ... long cut .. short cut
shortcut is take n = 1
1 + 2x + x2
2x is the term having greatest coefficient
2x > 1 ...... x >1/2
2x > x2 ...... x < 2
1/2 < x < 2
only b satisfies// shortcut because u can do this mentally
longcut
mid term has largest coefficient
2nCn xn > 2nCn+1 xn+1
(n+1)/n>x
similarly
n/n+1<x