Formula permutare: Pn = n! = 1*2*3*...*(n-1)*n
Formula aranjamente [tex]A_{n} ^k = \frac{n!}{(n-k)!}[/tex]
[tex]\frac{P_{3} -A_{3}^{0}}{P_{2} +A_{2}^{1}}=\frac{3! - \frac{3!}{(3-0)!} }{2!+\frac{2!}{(2-1)!} } = \frac{6-\frac{3!}{3!}}{2+\frac{2!}{1!}}= \frac{6-1}{2+2}=\frac{5}{4}[/tex]
