la factoriale tot timpul exprim nr mai mare in functie de cel mai mic ⇒(n-1)!*n}/(n-1)!+{(n-2)!(n-1)*n]/2(n-2)!=3 simplificam factorialele n+{(n-1)*n}/2=3aducem la num comun 2n+n^2-n=6 n^2+n-6=0 Δ1+24=25 x1=-1+5)/24/2=2 x2=-1-5)/2=-6/2=-3 e sol doar 2
