Question

(n+1)!/(n-1)!=56 peço ajuda para determinar o n fatorial

Answer 1

$\begin{array}{l}\frac{( n+1) !}{( n-1) !} =56\\\\\Longrightarrow \frac{( n+1) \cdotp n\cdotp \cancel{( n-1) !}}{\cancel{( n-1) !}} =56\\\\\Longrightarrow n^{2} +n=56\\\\\Longrightarrow n=-8\lor n=7\\\\n=-8\ \text{não\ serve,\ pois\ cairíamos\ em\ uma\ indeterminação}\\\\\therefore \boxed{n=7}\end{array}$