Binomialkoeffisienten

(x+y)^n = \sum \limits_{k=0}^n \binom{n}{k} x^{n-k} y^k

\chsfk{k}{n} = \frac{n!}{k!(n-k)!}

(2x+y)^6 = \sum \limits_{k=0}^6 \chsfk{n}{6} x^{6-k} y^k

(2x+y)^6 = \chsfk{6}{0}(2x)^{6-0}y^0 + \chsfk{6}{1}(2x)^{6-1}y^1.....

(2x+y)^6 = 64x^6 + 192x^5y+240 x^4y^2....