Question

How do we summarize 2×n 2n

Answer 1

Step-by-step explanation:

By definition 2n! is the number of ways one can arrange 2n distinct objects in 2n places. Second place by 2n-1, third by 2n-2 and so on such that rth place will be filled by 2n-r+1 choices . One interesting result can be obtained by separating the odd and even terms in the above multiplication.