Question

Need help with sequences. Find the eighth term of the sequence 5,-15,45,-135...

Answer 1

a1 a2 a3 a4 .........a8

5 -15 45 -135 .........n

a2/a1=-3

a3/a2=45/-15=-3

a4/a3=-135/45=-3

r=-3

finito generale:

progressione geometrica

`a_(n)=a_(1)*r^(n-1)\\ \\a_(n)=5*-3^(n-1)\\ \\`

sostituiamo n ----> 8

`a_(8)=5*-3^(8-1)\\ \\ \\a_(8)=5*-3^(7)\\ \\ \\a_(8)=5*-2187\\ \\ \\a_(8)=-10935`

the eighth term of the succession is:

-10935

greetings from Italy

Answer 2

the answer is -10,935

multiply -3 to each term to get the next one.