Given that the sequence {an} satisfies A1 = 1, (2n + 5) (an + 1) - (2n + 7) an = 4N ^ 2 + 24N + 35 (n ∈ n +), then the general term formula of sequence an is?

Given that the sequence {an} satisfies A1 = 1, (2n + 5) (an + 1) - (2n + 7) an = 4N ^ 2 + 24N + 35 (n ∈ n +), then the general term formula of sequence an is?

(2n + 5) a (n + 1) - (2n + 7) an = 4N & # 178; + 24N + 35 = (2n + 5) (2n + 7) both sides of the equation are divided by (2n + 5) (2n + 7) a (n + 1) / (2n + 7) - an / (2n + 5) = 1a (n + 1) / [2 (n + 1) + 5] - an / (2n + 5) = 1, which is the fixed value. A1 / (2 × 1 + 5) = 1 / 7 sequence {an / (2n + 5)} is an arithmetic sequence with 1 / 7 as the first term and 1 as the tolerance