An arithmetic sequence is 2,4,6,8,10 Then the tolerance is?

An arithmetic sequence is 2,4,6,8,10 Then the tolerance is?

Tolerance d = 4-2 = 2
The general term is an = 2 + 2 (n-1) = 2n

Let {an} be the arithmetic sequence with the first term of 50 and the tolerance of 2, and {BN} be the arithmetic sequence with the first term of 10 and the tolerance of 4. Take AK and BK as the largest circle area in the rectangle of the two adjacent sides and mark SK, then SK is equal to______ ．

∵ sequence {an} is an arithmetic sequence with 50 first term and 2 tolerance, ∵ an = 50 + 2 (n-1) = 2n + 48, ∵ {BN} is an arithmetic sequence with 10 first term and 4 tolerance, ∵ BN = 10 + 4 (n-1) = 4N + 6, let an ≥ BN, that is, 2n + 48 > 4N + 6, {n ≤ 21

In known arithmetic sequence {an}, an = 9, A9 = 3, find A1 and tolerance D

Are you sure you have the right number?
In the sequence {an}, an = 9, which is a constant sequence, where can A9 = 3 come from