Question

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

Answer 1

Find the difference first, can you do this?

Answer 2

this is a geometric series
where the next term is obtained multiplying by the common ratio

Answer 3

common ration=2 / -1

Answer 4

nth term = a1 *r^(n-1) where a1 = first term and r = common ratio

Answer 5

This is the formula.\[\huge {\color{blue} {\frac{a _{n}}{a _{(n-1)}}=ratio} }\]
The formula for GEOMETRIC SERIES.
For difference, sum, whetever you ned to find....
\[\huge {\color{blue} {S _{n}=\frac{a _{1}(1-r ^{n})}{(1-r)}} }\]