It is known that the positive term sequence {an}, {BN} satisfies the following conditions: for any positive integer n, an, BN, a (n + 1) are equal difference sequence, BN, a (n + 1), B (n + 1) are equal ratio sequence, And A1 = 10, A2 = 15 Verification: sequence (root BN) is arithmetic sequence General formula for solving sequence {an}, {BN} Let Sn = 1 / (A1) + 1 / (A2) + 1 / (A3) +. 1 / (an) for any positive integer n, the inequality 2asn

It is known that the positive term sequence {an}, {BN} satisfies the following conditions: for any positive integer n, an, BN, a (n + 1) are equal difference sequence, BN, a (n + 1), B (n + 1) are equal ratio sequence, And A1 = 10, A2 = 15 Verification: sequence (root BN) is arithmetic sequence General formula for solving sequence {an}, {BN} Let Sn = 1 / (A1) + 1 / (A2) + 1 / (A3) +. 1 / (an) for any positive integer n, the inequality 2asn

1. Let CN = root sign, BN be known by BN, a (n + 1), B (n + 1) in equal proportion sequence, an + 1 = CN times CN + 1, an, BN, a (n + 1) in equal difference sequence, 2cn square = an + an + 1 = Cn-1 times CN + CN times CN + 1, that is, 2cn = Cn-1 + CN + 1, that is, 2 root sign BN = root sign bn-1 + root sign BN + 1