C de n+1 luate cate n-2 = (n+1)!/(n+2)!*(n+1-n+2)!
(n+1)*(n+2)!/(n+2)!*3!= n+1/1*2*3=n+1/6
Combinari de n+1 luate cate n= (n+1)!/n!*(n-n+1)!
n!*(n+1)/n!*1= n+1
n+1/6+n+1=8 => n+1+6n+6=48 => 7n=48-7 => 7n=41 => n=41/7
Vezi sa nu fi gresit eu la calcule.
