Question

Given the sequence -1, 2, -4, 8, ..., identify the tenth term. Show your work.

Answer 1

look: 2/-1=-2
-4/2=-2
8/-4=-2 any ideas?

Answer 2

so the common ratio is -2

Answer 3

But what formula will help me find the 10th ?

Answer 4

To find any term
of an arithmetic sequence:
\[a _{n}=a _{1}+\left( n-1 \right)*d\]
where \[a _{1}\] is the first term of the sequence,
d is the common difference, n is the number of the term to find.

Answer 5

this is a geometric series, alexnader

Answer 6

you are incorrect

Answer 7

woops thx @idku

let me give another formula

Answer 8

To find any term of a geometric sequence:
where \[a _{1}\] is the first term of the sequence,
r is the common ratio, n is the number of the term to find.

\[a _{n}=a _{1}*r^\left( n-1 \right)\]

Answer 9

thx @idku for correcting me.