Answers

  • Brainly User
2016-07-08T12:18:09+08:00
Missing:  a₂, a₃. a₄, a₅, a₆

1)  Find the arithmetic mean, a₄:
(-9 + 9) / 2 = 0
a₄ = 0

2)  Find the common difference:
General formula:  an = a₁ + (n-1)(d)
an = 0    n = 4    a₁ = -9

0 = -9 + (4-1) (d)
0 = -9 + 3d
9 = 3d
3d/3 = 9/3
d = 3

Common difference: 3

3)  Find the rest of arithmetic means:
a₂ = -9 + 3
a₂ = -6

a₃ = -6 + 3
a₃ = -3

a₄ = -3 + 3
a₄ = 0

a₅ = 0 + 3
a₅ = 3

a₆ = 3 + 3
a₆ = 6

ANSWER:  The five arithmetic means are:  -6, -3, 0, 3, 6
The arithmetic sequence is:  -9, -6, -3, 0, 3, 6, 9

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