Home > A2C > Chapter 13 > Lesson 13.2.3 > Problem 13-135
13-135.
Each of the following sums is the beginning of an arithmetic series. Find the nth term of each series, for the specified value of n. Homework Help ✎
(−2) + (−5) + (−8) + …, n = 12
9 + 15 + 21 + …, n = 20
Set up an equation to describe the sequence.
t(n) = −2 − 3(n − 1)
Now substitute 12 for n to find the 12th term.
t(12) = −2 − 3(11)
−35
See part (a).