Question

Find the 17th term of the arithmetic sequence.
-6, 3, 12, 21, ...
The 17th term is

Answer 1

nth term = dn + (a - d) Where d is the difference between the terms, a is the first term and n is the term number.

Explanation:

9*17 + (-6- 9)= 138

Answer 2

First find the common difference.

This can be found by subtracting the second term minus the

first term which in this case us 3 - (-6) or 3 + (+6) which is 9.

So we add 9 to reach the next term in this sequence.

Since this sequence isn't too long, continuing adding 9

until you reach the 17th term in this arithmetic sequence.

-6 ⇒ 1st term

3 ⇒ 2nd term

12 ⇒ 3rd term

21 ⇒ 4th term

30 ⇒ 5th term

39 ⇒ 6th term

48 ⇒ 7th term

57 ⇒ 8th term

66 ⇒ 9th term

75 ⇒ 10th term

84 ⇒ 11th term

93 ⇒ 12th term

102 ⇒ 13th term

111 ⇒ 14th term

120 ⇒ 15th term

129 ⇒ 16th term

138 ⇒ 17th term

By manually doing this, we found that our 17th term is 138.