Question
Coefficient of x^ 13 in the expansion of (1-x)^ 5 (1+x+x^ 2 +x^ 3 )^ 4 is
BITSAT
Mathematics
Binomial Theorem
2021
BITSAT 2021
BITSAT Mathematics Question (2021) — Solution
Options
- A. 4
- B. 6
- C. 32
- D. 5
Answer
A. 4
Step-by-step solution
Expression =(1-x)^ 5 (1+x)^ 4 (1+x^ 2 )^ 4 array l =(1-x) (1-x^ 2 )^ 4 (1+x^ 2 )^ 4 \\ =(1-x) (1-x^ 4 )^ 4 array Coefficient of x^ 13 =- ^ 4 C _ 3 (-1)^ 3 =4
Related: Mathematics — Binomial Theorem · All PYQ Banks