For the geometric sequence

-1,-2,-4 ... find a8

Question

Mathematics

Myah Donaldson

21 November, 02:07

For the geometric sequence

-1,-2,-4 ... find a8

+2

Answers (2)

Know the Answer?

Sadie Little · Answer 1

An=a1 (r) ^ (n-1)

a1=first term

r=common ratio

so

firs term is - 1

each is double the prevoius

r=2

an=-1 (2) ^n-1

8th term

a8=-1 (2) ^ (8-1)

a8=-1 (2) ^7

a8=-1 (128)

a8=-128

the 8th term is - 128

Jessica Thompson · Answer 2

Geometric sequence formula gn = g1 (r) ^n - 1

To find the ratio you divide g2 by g1

G1 = first number in the series

To find g8 you just plug 8 instead of n

g8 = g1 (r) ^8 - 1

g8 = - 1 (2) ^8 - 1

g8 = - 128

For the geometric sequence-1,-2,-4 ... find a8

For the geometric sequence

-1,-2,-4 ... find a8