1.S=a^n+a^(n-1)b+a^(n-2)b^2+…… +ab^(n-1)+b^n(n∈N*,ab≠0) 2. Given that the general term formula of the sequence {an} is an = {- 6N + 5 (n is odd), find the first n terms and Sn of the sequence {2 ^ n (n is even)

1.S=a^n+a^(n-1)b+a^(n-2)b^2+…… +ab^(n-1)+b^n(n∈N*,ab≠0) 2. Given that the general term formula of the sequence {an} is an = {- 6N + 5 (n is odd), find the first n terms and Sn of the sequence {2 ^ n (n is even)

S=a^n+a^(n-1)b+a^(n-2)b^2+…… +ab^(n-1)+b^n (a-b)S=(a-b)[a^n+a^(n-1)b+a^(n-2)b^2+…… +AB ^ (n-1) + B ^ n] = [a ^ (n + 1) - B ^ (B + 1)] s = [a ^ (n + 1) - B ^ (B + 1)] / (a + b) n is odd number, then odd number has (n + 1) / 2 items, even number is (n-1) / 2 items