In the known arithmetic sequence {an}, a3a7 = - 16, A4 + A6 = 0, ① find {an} ② if D
Let the tolerance be d.1.a3 + A7 = A4 + A6 = 0a7 = - A3, substitute a3a7 = - 16-a3 & # 178; = - 16a3 = 4 or A3 = - 4A3 = 4, a7 = - A3 = - 4a7-a3 = 4D = (- 4) - 4 = - 8D = - 2A1 = a3-2d = 4-2 (- 2) = 8An = a1 + (n-1) d = 8 + (- 2) (n-1) = 10-2n, then the general formula of the sequence {an} is an = 10-2na3 = - 4, a7 = - A3
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