Published by:
CGP EDU Academic Team
Published on: August 13, 2026
In the expansion of 
, n ∈ N, if the sum of the coefficients of x 5 and x 10 is 0, then n is :
Text Solution
Verified by ExpertsThe correct answer is:
15
(15)
Sol. 
General term = 
(–1) n–r x 5r–2n
If 5r – 2n = 5, then 5r = 2n + 5 ⇒ r = 
+ 1
If 5r – 2n = 10, then 5r = 2n + 10 ⇒ r = 
+ 2
Let n = 5k
Now 
– 
= 0
⇒ 
– 
= 0 ⇒ k = 3 ⇒ n = 15
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