Question

resolva a equação Cn,2+Cn+1,n-1 = 25

Answer 1

Resposta:

$\textsf{Leia abaixo}$

Explicação passo a passo:

$\mathsf{C_{n,2} + C_{n+1,n - 1} = 25}$

$\mathsf{\dfrac{n!}{2!.(n - 2)!} + \dfrac{(n + 1)!}{(n - 1)!.2!} = 25}$

$\mathsf{\dfrac{n.(n - 1).(n - 2)!}{2!.(n - 2)!} + \dfrac{(n + 1).n.(n - 1)!}{(n - 1)!.2!} = 25}$

$\mathsf{n.(n - 1) + n.(n + 1) = 25}$

$\mathsf{n^2 - n + n^2 + n = 25}$

$\mathsf{2n^2 = 25}$

$\mathsf{n = \dfrac{5}{\sqrt{2}}}$

$\boxed{\boxed{\mathsf{n = \dfrac{5\sqrt{2}}{2}}}}$