Răspuns:
C₁₁⁹-C₁₁²=C₁₁¹¹⁻⁹-C₁₁²=
C₁₁²-C₁₁²=0S-a folosit formula
Cₙˣ=Cₙⁿ⁻ˣ
Metoda 2
Cₙˣ=n!/x!*(n-x)!
C₁₁⁹-C₁₁²=
11!/9!(11-9)!-11!/2!(11-2)!=
11!/9!*2!-11!/2!*9!=0
Explicație pas cu pas:
C11 luate cate 9=C11 luate cate (11-9)=C11 luate cate 2
Cn luate luate cate k=n!/k!(n-k)!
Cn luate cate k=Cn luate cate (n-k)
C11 luate cate 2-C11 luate cate 2=0
