Question

resolva a equação (n-2)!=20(n-4)!

Answer 1

n! / (n-2)!=12 ----- 
n(n-1)(n-2)!/(n-2)!=12 ------ 
n(n-1)=12------ 
n2-n=12 
n2 -n-12=0 
n= 1+√(1+49)/2 
n= 1+7/2 = 4 ------ n=4 

(n!-n)=4.3.2.1 - 4=24-4=20 
*(n!-n)=20*