BITSAT2018MathematicsBinomial TheoremActual
The coefficient of x - n in 1 + x n 1 + 1 x n is
Options
- A0
- B1
- C2 n
- D2 n
Correct answer
B. 1
Step-by-step solution
1 + x n 1 + 1 x n = 1 + x 1 + 1 x n 1 + x n 1 + 1 x n = 1 + x + 1 x + 1 n 1 + x n 1 + 1 x n = 2 + x + 1 x n 1 + x n 1 + 1 x n = C 0 n 2 + x n · 1 x + C 1 n 2 + x n - 1 · 1 x 1 + … + C n n · 1 x n ∴ Coefficient of x - n = C n n = 1