Answers

  • Brainly User
2016-06-25T21:41:44+08:00
Find the formula for the nth term of the (NOT EACH because you wrote only one set of sequence)  of arithmetic sequence 38, 28, 18, 8.

First, find the common difference between the consecutive terms.
a₁=38      a₂=28      a₃=18      a₄=8

a₂ - a₁ = 28 - 38 = -10
a₃ - a₂ = 18 - 28 = -10
a₄ - a₃ = 8 - 18 = -10

d = -10      a₁=38

General rule/formula:     an = a₁ + (n-1) (d)

Rule (formula) for the given sequence 38, 28, 18, 8

an = 38 + (n-1)(-10)

an = 38 -10n + 10

an = -10n + 38 + 10

an = -10n + 48

ANSWER:   a_{n} = -10n + 48

To check:
a₁ = 38
a₁ = -10(1) + 48
a₁ = -10 + 48
a₁ = 38    (True)

a₂ = 28
a₂ = -10(2) + 48
a₂ = -20 + 48
a₂ = 28   (True)

a₃ = 18
a₃ = -10(3) + 48
a₃ = -30 + 48
a₃ = 18

You can do the checking for the last term, a₄.

0