PLEASE explain each step descriptively I am very lost at how they came across the answers to each step

3) (10 pts) ANL (Summations) What is the closed form of the following summation? Your solution should be a function in terms of n. For full credit work must be shown. ni 2! i=0 =0 ni n 2! =(2161 - 1) i=0 /=0 i=0 n n 1 1 i=0 n i=0 2+1 = X(2)2 (n+1) = 221 (n + 1) i=0 n i=0 = 2(21+1 1) - (n+1) = 2n+2 - 2-n-1 = 2n+2 - n-3 Grading: 3 pts inner sum 1 pt split 1 pt second sum 4 pts first sum (lots of ways to break this down) 1 pt simplification at the end