a 1×a4=a2×a3=8 ①

∫a 1+a4 = 9②

Simultaneous ① ②, the solution is a 1= 1, a4=8 or a 1=8, a4= 1.

∵ q> 1 is known, so a 1= 1, a4=8.

∴q？ =a4/a 1=8,∴q=2

To sum up, a 1= 1, q=2.

s6=a 1*( 1-q^6)/( 1-q)= 1*( 1-2^6)/( 1-2)=63