Sequence (17 16:56:38) If {an} satisfies: a1 + A2 + a3 + A4 + A5 = 3, A12 + A22 + A32 + A42 + a52 = 12, then the value of a1-a2 + a3-a4 + A5 is:    

Sequence (17 16:56:38) If {an} satisfies: a1 + A2 + a3 + A4 + A5 = 3, A12 + A22 + A32 + A42 + a52 = 12, then the value of a1-a2 + a3-a4 + A5 is:    

A1-a2 + a3-a4 + A5 = a1-a1-d + A1 + 2d-a1-3d + A1 + 4D = a1 + 2D = A3 ∵ equal ratio sequence {an}, a1 + A2 + a3 + A4 + A5 = 3, (a1 + A5) + (A2 + A4) + a3 = 2 × A3 + 2 × A3 + a3 = 5 × A3 = 3, ∵ A3 = 3 / 5 ∵ a1-a2 + a3-a4 + A5 = A3 = 3 / 5

Two questions about sequence (27 19:56:36)
1. The first n terms of sequence an & # 160; and Sn = an + 1 (n ∈ positive integer), A1 = 2, find an & # 160; and Sn
2. In the sequence an & # 160, A1 = 2, an & # 160; = an-1 + 2n (n 〉 1), find the general term formula an

1. Sn = a (n + 1) s (n-1) = ansn-s (n-1) = a (n + 1) - an = ana (n + 1) = 2anan is an equal ratio sequence with a common ratio of 2. When A1 = S1 = A2 = 2n = 1 and an = 2n ≥ 2, an = 2 ^ (n-1) Sn = 2 ^ N2. An-a (n-1) = 2Na (n-1) - A (n-2) = 2 (n-1) a (n-2) - A (n-3) = 2 (n-2)... When a2 - A1 = 2 * 2, add the above formula to get an

llllllllllllllllllllllllllllllllllllllllllllllllll (18 11:40:56)
Given the function f (x) = ax + B, if f (0) = 1 and f (x + 1) = f (x + 1) = f (x) + 3, find f (x)

If we take F (0) and get b = 1, then f (x + 1) = a (x + 1) + 1, f (x) + 3 = ax + 4
Then f (x + 1) = f (x) + 3, i.e. a (x + 1) + 1 = ax + 4 is reduced to a = 3
So f (x) = 3x + 1

Seeking sequence: 4,18,56130, ()
A.252 B.254 C.253 D.250

4=2*(1^3+1)
18=2*(2^3+1)
56=2*(3^3+1)
130=2*(4^3+1)
The next one is 2 * (5 ^ 3 + 1) = 252