## anonymous one year ago Will fan and Medal. Find the 8th term of the geometric sequence. 1, -2, 4, -8,

1. SolomonZelman

what pattern do you notice here?

2. anonymous

It's going back from positive to negative. But the middle numbers its jumping up and down each time.

3. SolomonZelman

you are multiplying times -2 each time, right?

4. SolomonZelman

so, starting from the 1st term, you need to multiply times -2 once to get to the second term.

5. anonymous

And you'd keep going from there correct?

6. SolomonZelman

and starting from 1st term, you need to multiply times -2, 2 times , to find the 3rd term

7. SolomonZelman

and starting from the 1st term, you need to multiply times -2, 3 times, to find the 4th term

8. SolomonZelman

this way, you need to multiply times -2, 'n-1' number of times, to find the nth term.

9. SolomonZelman

and so, you need to multiply times -2, 7 times to find the 8th term

10. anonymous

Oh, I see what you are doing there.

11. SolomonZelman

$$1\times (-2)^7=a_8$$

12. SolomonZelman

see why this is the 8th term?

13. SolomonZelman

(and all you need to do is to calculate that) I got to go, apologize, and you welcome.

14. anonymous

Yes, I understand now. I was confused but I think you gave me a very easy way how to solve it. Thank you!