COMEDK2023MathematicsBinomial Theorem
The coefficient of x²⁹ in the expansion of (1-3 x+3 x^2-x^3 )¹⁵ is
Options
- A45 29
- B45 28
- C- 45 16
- D45 30
Correct answer
C. - 45 16
Step-by-step solution
(1-3 x+3 x^2-x^3 )¹⁵= [(1-x)^3 ]¹⁵=(1-x)⁴⁵ So, T_ r+1 = ⁴⁵ C_r(1)^ 45-r (-x)^r For coefficient of x²⁹ , put r=29 Then, T₃₀= 45 29 (1)⁴⁵⁻²⁹(-x)²⁹=- 45 29 x²⁹ Hence, coefficient of x²⁹=- 45 29 and - 45 29 =- 45 16