Question

Given a2=-18, a5=2/3, get a6

Answer 1

completely blanked out and forgot how to do this

Answer 2

\[a_2=-18\\
a_3=a^2r\\
a^4=a_2r^2\\
a_5=a_2r^3\] put \[-18\times r^3=\frac{2}{3}\] and solve for \(r\)

Answer 3

typo there, i meant \(a_3=a_2r\)

Answer 4

no use of any formulas can be used here?

Answer 5

to get a1 or r?