Question

Find the 7th term of the geometric sequence with a3= -45 and a5= -405

Answer 1

Explanation:

let a be the first term and r be common ratio.

`a_(3)=ar^2=-45\\a_(5)=ar^4=-405\\divide\\(ar^4)/(ar^2) =(-405)/(-45) =9\\r^2=9\\r=\pm3\\9a=-45\\a=-5\\a_(7)=ar^(7-1)=ar^6=ar^4 * r^2=-405 * 9=-3645`