## anonymous one year ago What are the next three terms of the sequence 1, -3, 9, -27,…? A. -54, 162, -486 B. -81, 243, -729 C. 81, -243, 729 D. 57, -162, 486

1. tkhunny

Ridiculous problem. Finite sequences have infinitely many "next three terms". ANYTHING you can justify is an acceptable answer. 1, -3, 9, -27, 0, -2, 5 -- That works. 1, -3, 9, -27, 28, -29, 5 -- That works. 1, -3, 9, -27, $$\sqrt{5}$$, $$\pi$$, e -- That works. What say you? Give us a clue what YOU might think are three acceptable values and justify your response.

2. anonymous

Well, I thought it was 57, -162, 486, but I really wasn't sure, so I came on here for some help..

3. tkhunny

It's not a matter of being sure. It's a matter of justifying your answer. How did you get those three values?

4. anonymous

If you're having trouble with this, try breaking it down. The sequence itself has 4 values in it already. What did the 1 do to become -3?

5. tkhunny

Generally, it's a good idea to look for common differences or common ratios. Subtract each successive pair. What do you get? Divide each successive pair. What do you get?

6. anonymous

i really don't understand

7. Loser66

1*(-3) =?

8. anonymous

-3

9. Loser66

Now, second term -3*(-3) =?

10. anonymous

9

11. Loser66

Now, third term 9*(-3) =?

12. anonymous

-27

13. Loser66

can you see your answers are the term of the given sequence??

14. anonymous

oh, yeah! Thank you so much! I get it now :)

15. Loser66

so, next will be???

16. anonymous

81

17. anonymous

then it'll be -243

18. Loser66

Yes!! look at your options, which is correct.

19. anonymous

c! Thanks again :)

20. Loser66

No need to do next, since there is only 1 option which starts at 81, It is C

21. Loser66

YOu got it. hehehe...