Question

ARRANJO
Resolva a equação seguinte:
 An+2 ,n+1 = 120


resposta: S = {       }

Answer 1

$A_{n,p}=n!/(n - p)!$
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$A_{n+2,n+1}=120\\(n + 2)! / (n+2-n-1)!=120\\(n+2)!/1!=120\\(n+2)!=120\\(n+2)!=5!\\n+2=5\\n=5-2\\n=3$