Combinarii, aranjamnte si binmul lui Newton

Question 1

C de n luate cate k

Answer 1

n!/k! (n-k)!

Question 2

A de n luate cate k

Answer 2

n!/(n-k)!

Question 3

Binomul lui Newton

Answer 3

C de n luate cate k * a^ n-k * b^k