Question

Combinari de x lata cate 2 plus aranjamente de x late cate 2 egal cu 3

Answer 1

x!/2!*(x-2)! +x!/(x-2) = 3
(x-2)! (x-1) x / 2!(x-2)! + ( x-2)! (x-1) x/ ( x-2)
Dupa simplifici (x-2)! in ambele fractii , inmultesti parantezele..2!=3 si restul e de la sine :)))