Suku ke-3 dan suku ke-6 deret geometri berturut turut adalah 48 dan 384. Jumlah 5 suku pertama adalah...
IcukSugiarto
![\bold{\underline{Solution:}}\\\\rumus\ umum:\\\boxed{U_{n}=a.r^{n-1}}\\\\sehingga\ untuk\ suku\ ke\ 3:\\U_{3}=a.r^{2}=48...........(1)\\\\untuk\ suku\ ke\ 6:\\U_{6}=a.r^{5}=384...............(2)\\\\subtitusi\ persamaan:\\a.r^{5}=384\\a.r^{2}.r^{3}=384\\48 \times r^{3}=384\\r^{3}= \frac{384}{48}\\r^{3}=8\\r= \sqrt[3]{8}\\r=2](https://tex.z-dn.net/?f=%5Cbold%7B%5Cunderline%7BSolution%3A%7D%7D%5C%5C%5C%5Crumus%5C+umum%3A%5C%5C%5Cboxed%7BU_%7Bn%7D%3Da.r%5E%7Bn-1%7D%7D%5C%5C%5C%5Csehingga%5C+untuk%5C+suku%5C+ke%5C+3%3A%5C%5CU_%7B3%7D%3Da.r%5E%7B2%7D%3D48...........%281%29%5C%5C%5C%5Cuntuk%5C+suku%5C+ke%5C+6%3A%5C%5CU_%7B6%7D%3Da.r%5E%7B5%7D%3D384...............%282%29%5C%5C%5C%5Csubtitusi%5C+persamaan%3A%5C%5Ca.r%5E%7B5%7D%3D384%5C%5Ca.r%5E%7B2%7D.r%5E%7B3%7D%3D384%5C%5C48+%5Ctimes+r%5E%7B3%7D%3D384%5C%5Cr%5E%7B3%7D%3D+%5Cfrac%7B384%7D%7B48%7D%5C%5Cr%5E%7B3%7D%3D8%5C%5Cr%3D+%5Csqrt%5B3%5D%7B8%7D%5C%5Cr%3D2 "\bold{\underline{Solution:}}\\\\rumus\ umum:\\\boxed{U_{n}=a.r^{n-1}}\\\\sehingga\ untuk\ suku\ ke\ 3:\\U_{3}=a.r^{2}=48...........(1)\\\\untuk\ suku\ ke\ 6:\\U_{6}=a.r^{5}=384...............(2)\\\\subtitusi\ persamaan:\\a.r^{5}=384\\a.r^{2}.r^{3}=384\\48 \times r^{3}=384\\r^{3}= \frac{384}{48}\\r^{3}=8\\r= \sqrt[3]{8}\\r=2")
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Thanks 1
zhangaina
thanks you teacher
IcukSugiarto
iya, sama-sama dek, senang bisa membantu...
zhangaina
ya kakak