Question

C5 la a doua + a cinci la doua - p trei

Answer 1

 

Daca ai postat exercitiul asta, inseamna ca ti s-a predat la scoala
elemente de combinatorica.
In acest caz trebuia sa stii cum se citesc:
.
$\displaystyle\bf\\C_5^2~~~se~citeste:~Combinari~de~cinci~luate~cate~doua.\\\\A_5^2~~~se~citeste:~Aranjamente~de~cinci~luate~cate~doua.\\\\P_3~~~se~citeste:~Permutari~de~trei.\\\\Rezolvare:\\\\C_5^2+A_5^2-P_3\\\\=\frac{A_5^2}{P_2}+ A_5^2-P_3=\\\\\\=\frac{A_5^2}{P_2}+ A_5^2-P_3=\\\\\\=\frac{5\times4}{1\times2}+ 5\times4-(1\times2\times3)=\\\\\\=\frac{20}{2}+ 20-6=\\\\\\=10+20-6=30-6=\boxed{\bf24}$