Published by:
CGP EDU Academic Team
Published on: August 12, 2026
Prove that 2 k 
– 
+ 
–...... + (– 1) k 
= 
.
Text Solution
Verified by ExpertsThe correct answer is:
CHECK THE SOLUTION.
S = 2 k n C 0 . n C k – 2 k–1 n C 1 n–1 C k–1 + 2 k–2 n C 2 n–2 C k–2 +.............
⇒ S = 
n C r n–r C k–r . 2 k–r ⇒ S = 
× 
= 
× 
= 
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