CPM Homework Help : CCA2 Problem 10-18

A series has $9$ terms. The last term is $18$ , and the fifth term is $6$ . What is the series?

Hint 1:

Find the sequence that corresponds to the terms of the series.

Hint 2:

$t(5) = 6 = (5)a + b$
$t(9) = 18 = (9)a + b$

Hint 3:

$a = -3$ and $b = -9$

Hint 4:

Now use the sequence to find the rest of the terms of the series.

Answer:

$(-6) + (−3) + 0 + 3 + 6 + 9 + 12 + 15 + 18$