BITSAT2024MathematicsBinomial TheoremActual
If the 17^ th and the 18^ th terms in the expansion of (2+a)⁵⁰ are equal, then the coefficient of x³⁵ in the expansion of (a+x)⁻² is
Options
- A-35
- B3
- C36
- D-36
Correct answer
D. -36
Step-by-step solution
Given, 17^ th and 18^ th terms in the expansion (2+a)⁵⁰ are equal T₁₇=T₁₈ 50 16 (2)³⁴(a)¹⁶= 50 17 (2)³³(a)¹⁷ a= 50 16 50 17 2=1 Now, coefficient of x³⁵ in the expansion (1+x)⁻²=-36 Coefficient of x^r is (r+1) in (1-x)⁻² .