NDA2021MathematicsBinomial TheoremActual
Consider the expansion of (1+x)^n . Let p, q, r and s be the coefficients of first, second, n^ th and (n+1)^ th terms respectively. What is ( p s+q r ) equal to?
Options
- A1+2 n
- B1+2 n^2
- C1+n^2
- D1+4 n
Correct answer
C. 1+n^2
Step-by-step solution
According to question aligned & p= ^n C₀=1, q= ^n C₁=n & r= ^n C_ n-1 = ^n C₁=n and S= ^n C_n=1 & p s+q r=1 1+n n=1+n^2 aligned