Jawabanmu

2014-05-29T17:02:50+07:00
Ar = 2 dan ar^4 = 54
ar^4/ar = 54/2
r³ = 27 = (3)³ berarti r = 3
ar = 2 ⇔ 3a = 2 ⇔ a= 2/3

U4 = ar³ = (2/3)(3)³ = (2/3)(27) = 18
Jawaban paling cerdas!
2014-05-29T19:04:48+07:00
 U_{2} = 2
 U_{5} = 54

ar = 2 ---> a × 3 = 2 ---> a =  \frac{2}{3}
a r^{4} = 54
2 ×  r^{3} = 54
 r^{3} = 54 ÷ 2
 r^{3} = 27
r = 3

 U_{4} = a r^{3}  \frac{2}{3}  ×  3^{3} = 18

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