NTA Abhyas JEE Main2020MathematicsBinomial TheoremPractice
The value of ∑ i = 1 n C n + 1 i - C n i is equal to
Options
- A2 n
- B2 n + 1
- C3 ⋅ 2 n
- D2 n - 1
Correct answer
D. 2 n - 1
Step-by-step solution
C n + 1 i - C n i = C n i + C n i - 1 - C n i = C n i - 1 ⇒ Sum = C 0 n + C 1 n + … + C n - 1 n = 2 n - C n n = 2 n - 1