Question

Determinati numarul submultimilor cu 3 elemente ale unei multimi care are 5 elemente.

Answer 1

Combinari de 5 luate cate3=5!/(3!*2!)=4*5/2=10

Answer 2

$\it C^3_5 = \dfrac{5!}{3!\cdot(5-3)!} = \dfrac{5!}{3!\cdot2!} = \dfrac{3!\cdot4\cdot5}{3!\cdot1\cdot2} = \dfrac{20}{2} = 10$