barisan geometri 4,8,16....hitunglah 7 suku pertama

a = 4
r = 8/4 = 2
U7 = a x r^n-1
      = 4 x 2^7-1
      = 4 x 2^6
      = 4 x 64
      = 256

a = 4
rasio = U2/U1 = 2

Un = a × r^n-1
U7 = a × r^6
U7 = 4 × 2^6
U7 = 4 × 64
U7 = 256

Semoga Membantu