Question

Write an arithmetic sequence that has a common difference of -3 and whose

fourth term is 17. *
Your answer
​

Answer 1

Explanation:

arithmetic sequences can be written as

`a_n = a_1 + (n-1)d\\`

in this case

`a_n = a_1 + (n-1)(-3)\\and\\17 = a_1 +(4-1)(-3)\\17= a_1 + (3)(-3)\\17= a_1 - 9\\a_1 = 26\\so\\a_n = 26 - 3(n-1)\\a_n = 26 -3n + 3\\a_n = 29 - 3n`