This week we learned about geometric sequences and series. A Geometric sequence differs from an arithmetic sequence because instead of adding a common difference, a common ratio is multiplied by the term to get the next term.

the equation used to find a term in a sequence is

$t_n=ar^{n-1}$

in this equation $t_1$ is represented by $a$

for example: 5,10,20,40… find $t_{10}$

$t_{10}=5(2)^{10-1}$

$t_{10}=5(2)^9$

$t_{10}=5(512)$

$t_{10}=2560$

A finite geometric series can be found using the equation