Problem 8

Problem – 8

Find the coefficient of in .

 

Solution:

Binomial theorem for (x+y)ⁿ = ⁿC₀xⁿy⁰ + ⁿC₁x^n-1y¹+ ⁿC₂x^n-2y² + ⁿC₃x^n-3y³ +…………+ ⁿC_n-1x¹y^n-1+ ⁿC_nx⁰yⁿ

Using the Binomial theorem, coefficient of x⁸y⁵ = ¹³C_(13-5) = ¹³C₈ = 1287