Pertanyaan

Diketahui deret geometri dengan suku pertama 3 dan suku ke empat adalah 24. Jumlah enam suku pertama deret tersebut adalah...

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Klaim

Y. Laksmi

Master Teacher

Mahasiswa/Alumni Universitas Negeri Semarang

Jawaban terverifikasi

Pembahasan

$S u k u space p e r t a m a space equals a equals 3 S u k u space k e space e m p a t space equals U subscript 4 U subscript 4 equals a r cubed equals 24 space space space space space space space space space 3 r cubed equals 24 space space space space space space space space space space space r cubed equals 24 over 3 space space space space space space space space space space space r cubed equals 8 space space space space space space space space space space space space space r equals 2 J u m l a h space e n a m space s u k u space p e r t a m a space equals space S subscript 6 S subscript 6 equals fraction numerator a open parentheses r to the power of n minus 1 close parentheses over denominator r minus 1 end fraction space space space space space space equals fraction numerator 3 open parentheses 2 to the power of 6 minus 1 close parentheses over denominator 2 minus 1 end fraction space space space space space space equals fraction numerator 3 open parentheses 64 minus 1 close parentheses over denominator 1 end fraction space space space space space space equals 189$