Find the next four terms of the arithmetic sequence 21,15,9 Answer: The next four terms are: 3, -3, -9, -15. Step-by-step explanation: The first 3 terms of the sequence: 21, 15, 9 (decreasing sequence) a₁ = 21 a₂ = 15 a₃ = 9 Find the common difference (d): a₂ - a₁ = a₃ - a₂ 15 - 21 = 9 - 15 -6 = -6 d = -6 Find the next four terms a₄, a₅, a₆, a₇: a₄ = a₃ + d a₄ = 9 + (-6) a₄ = 3 a₅ = 3 + (-6) a₅ = -3 a₆ = -3 + (-6) a₆ = -9 a₇ = -9 + (-6) a₇ = -15 The next four terms are: 3, -3, -9, -15. The sequence: 21, 15, 9, 3, -3, -9, -15.
Comments
Post a Comment