Question

C n luarea te 0+ 2 înmulțit cu C de n luate cate 1 =7

Answer 1

   C _{n} ^{0}= \frac{n!}{0!(n-0)!}= \frac{n!}{1*n!}=1 \\      C _{n} ^{1}= \frac{n!}{1!(n-1)!}= \frac{(n-1)!n}{(n-1)!}=nEcuatia initiala este:1+2n=72n=6n=3