Equal product and equal difference sum formula!

Arithmetic sequence: SN = (a1 + an) n / 2, Sn = n (2A1 + (n-1) d) / 2; (D is tolerance) Sn = an2 + BN; a = D / 2, B = A1 - (D / 2) arithmetic sequence: SN = n × A1 (Q = 1) Sn = A1 (1-Q ^ n) / (1-Q) = (a1-an * q) / (1-Q) (Q ≠ 1) s ∞ = A1 / (1-Q) (n - > ∞) (| q)|

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