1. anonymous

Don't think so. The common ratio is -2.

2. welshfella

none of them are correct common ratio = -10 according to the question.

3. anonymous

Common ratio is any term divided by the term immediately preceding it.$\frac{ -10 }{ 5 } = -2$

4. welshfella

oh sorry I misread the question The second term is -10.!!!

5. welshfella

as ospreytriple has said the common ratio r can be found by second term / first term = -10 / 5

6. anonymous

In general,$a_n = a_1\left( r \right)^{n-1}$For the first term (n=1) you would get$a_1=a_1\left( r \right)^{1-1} = a_1$In your question, $$a_1 = 5$$ and $$r = -2$$

7. welshfella

hint: first term is when n = 1

8. anonymous

Well, if you think the answer is B, try n=0 and see what you get.

9. anonymous

Correct.

10. welshfella

its A

11. vera_ewing

Thank you

12. anonymous

You're welcome