Published by:
CGP EDU Academic Team
Published on: August 13, 2026
If n is even natural and coefficient of x r in the expansion of 
is 2 n , (|x| < 1), then prove that 
Text Solution
Verified by ExpertsThe correct answer is:
CHECK THE SOLUTION.
y = (1 – x) –1 (1 + x) n
y = (1 + x + x 2 +... ∞ ) (1 + x) n
y = (1 + x) n + x(1 + x) n + x 2 (1 + x) n + ....
Co-efficient of x r =
n C r + n C r–1 + .... n C 0 = 2 n
r > n (As n C n+1 ) = 0
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