Question

Find an explicit rule for the nth term of the sequence.

-3, -15, -75, -375, ...

Answer 1

Can you identify the first term of this sequence?
Now look at the given terms from left to right. How do you obtain each term from the term that precedes it? Your answer provides the "common multiple" of the sequence.

Answer 2

you multiply by 5 each time

Answer 3

okay...

Answer 4

Thus, one way of writing the general term of the sequence would be (-3)*5^(n-1), with n starting at 1. Try it...let n = 1, 2, 3, 4, etc., and see whether this general term correctly predicts the given terms of the sequence in question.

Answer 5

Verify that this general term actually "works."

Answer 6

Kate: if n = 1, evaluate (-3)*5^(n - 1). Is the result what you expected? (Refer to the given, original sequence.)

Answer 7

Sorry, I was distracted. Im doing two things at once, so I was confused at first, I get it mow though thanks for your help. :)

Answer 8

You're welcome!