Respuesta :

By the binomial theorem, we have

[tex](x+y)^8=\displaystyle\sum_{k=0}^8\binom8kx^{8-k}y^k[/tex]

where [tex]\dbinom8k=\dfrac{8!}{k!(8-k)!}[/tex]. The 7th term occurs when [tex]k=6[/tex], which gives

[tex]\dbinom86x^{8-6}y^6=28x^2y^6[/tex]