Question

Suku ke- 4 suatu barisan geometri adalah 375, jika U1= 3, maka U6= ?

Answer 1

U1 = a = 3

U4 = ar^4-1
375 = ar^3
375 = 3 x r^3
r^3 = 375 : 3
r^3 = 125
r = ∛125
r = 5

U6 = ?
U6 = ar^6-1
U6 = 3 x 5^5
U6 = 3 x 3125
U6 = 9375

Answer 2

Diket : U1 = 3 / a = 3
           U4 = 375
U4 = a*r^(4-1)
U4 = 3*r^3 = 375
     = r^3 = 375 / 3
     = r^3 = 125
     = r = 5
Jadi U6 =
 = 3*5^5
 = 3*3125
 = 9375