a2? =a 1a3
a 1a2a3=2 16
So a2? =2 16
a2=6
a 1=6/q,a3=6q
Then 6/q+6+6q=26.
Multiply both sides by q
3q? - 10q+3=0
(3q- 1)(q-3)=0
q= 1/3,q=3
So it's 2,6, 18 or18,6,2.