Given the geometric sequence an with the following information, find a9.

Question

a5=192

a9=-512/9

Select the correct answer below:

a9=1024/27

a9=−512/9

a9=−2048/81

a9=4096/243

Answer 1

a9=-512/9

Is this a trick question? You're given that a9 =-512/9

if this is a geometric sequence, the signs should be alternating, yet a5 is +, a6 - a7 + a8 - a9 should be +

something doesn't look right. ar^n with r= common ratio means r is negative to get an a9 negative, but then a5 would be negative also. It's not a geometric sequence as given.