Question

calcule ou simplifique (n-1)!/(n-3)!​

Answer 1

(n-1)!/(n-3)!= (n-1).(n-2).(n-3)!/(n-3)!=

(n-1).(n-2)= n^2-2n-n+2

n^2-3n+2=0

Delta=b^2-4.a.c

Delta=(-3)^2-4.1.2

Delta=9-8

Delta=1

x1=-(-3)+1/2=2

x2=-(-3)-1/2=1

X1=2

X2=1