Thread: Finding the next four terms of this sequence?

5n, -n, 7n...

2a-5, 2a+2, 2a+9...

I'm having trouble with the variables. Any problem solving help?

Originally Posted by puzzledwithpolynomials

3, 4.5, 6...
My brain is just not working today? I don't know. I was thinking to maybe use the sequence forumla and try to derive it from there?
Also:
5n, -n, 7n...

For the simplest n'th term sequence, the formula is where is the difference between the terms, is the first initial term and is the term number. Thus for , the difference between the term ( ) is , the first term ( ) is thus the formula is .

For the second, do you mean ? This would make the difference , the first initial term and thus you would be able to use the n'th term formula.

Originally Posted by puzzledwithpolynomials

5n, -n, 7n...

2a-5, 2a+2, 2a+9...

I'm having trouble with the variables. Any problem solving help?

Hi puzzled,

Are you sure about the first 3 terms of your first sequence? It would be nice if it were:

5n, -n, -7n

Then the common difference would be -6n. You simply add -6n four more times to get your four terms.

In the second one, 2a-5, 2a+2, 2a+9, you have a common difference of 7. Looks like each successive term is 7 more than the previous one. So, just add 7 four more times to get the next four terms.