Question

What is the 7th term of the geometric sequence -1, 3, -9, ...?

Answer 1

What is the common ratio, can you tell me ?

Answer 2

the common ratio is -3

Answer 3

the first term is -1

would the formula look like ar^n - 1?

Answer 4

(-1)(-3)^(7 - 1)

Answer 5

For any term in the sequence where a1 is the first term.

\[\huge\color{blue}{ a_n=a_1 \times r^{n-1} } \]

Answer 6

In your case,

\[\huge\color{blue}{ a_7=(-1) \times (-3)^{7-1} } \]Makes sense ?

Answer 7

Yes! Thank you!

Answer 8

Good, tell me what you get for the term, when you are done.

Answer 9

-729 :)

Thank you for helping me!

Answer 10

yes, that is correct. Anytime!