Published by:
CGP EDU Academic Team
Published on: August 12, 2026
The sum 
(r + 1) C r2 is equal to :
A
B
C
D
Text Solution
Verified by ExpertsThe correct answer is:
A
(1+x) n = C 0 + C 1 x +............+ C n x n
Multiply by x & then differentiate
(1+x) n + x. n(1+x) n–1 = C 0 + 2C 1 x +............+ (n+1)C n x n ..................(i)
and (x+1) n = C 0 x n + C 1 x n–1 +............+ C n ..........(ii)
Multiply (i) & (ii) & equate the coefficient of x n on
both side
C 02 + 2C 12 + ........+ (n + 1) C n2 = 2n C n + n. 2n–1 C n–1 = 
= 
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