Question

What is the value of the 24th term in the following arithmetic sequence?

-9, -2, 5, 12, ...

-170
152
-200
170

Answer 1

152

Explanation:

this is an arithmetic sequence, since the gap between values is the same (-2 - -9 = 7, 5 - -2 = 7......)

the first value, a, is -9. the common difference is 7. n is position in sequence.

formula for arithmetic sequence = a + (n-1)d

= -9 + (n-1) 7

= -9 + 7n -7

=7n -16.

so the 24th term is 7(24) - 16

= 152.