bantuuuu plissss, makasih

U5=ar^4= 64
U3=ar^2=16
------------------ :(dibagi)
r^2 = 4
r = 2

subtitusi :
a(2)^2 = 16
4a = 16
a = 4

jumlah 10 suku pertama:
S10= a(r^10 -1)/r-1
= 4(2^10 - 1)/2-1
= 4(1024-1)/1
=4(1023)
= 4092

Semoga membantu
Sorry kalo salah