Question

Urgent va rog.Ofer 40 de puncte!

Answer 1

$C_{x+1}^{x-4} = \dfrac{7}{15}A_{x+1}^3 \Longleftrightarrow \dfrac{(x+1)!}{(x-4)!\cdot5!} = \dfrac{7}{15}\dfrac{(x+1)!}{(x-2)!}$

Dupa simplificari, se ajunge la:

$\dfrac{1}{8} = \dfrac{7}{(x-3)(x-2)} \Longrightarrow x = 10.$