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Suatu deret geometri mempunyai suku ke-2=8 dan suku ke-6=2.048. Jumlah 5 suku pertama adalah ...

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$I n g a t factorial R u m u s space s u k u space k e minus n comma space y a i t u colon U subscript n equals a r to the power of n minus 1 end exponent r u m u s space j u m l a h space s a m p a i space s u k u space k e minus n space a d a l a h S subscript n equals fraction numerator a left parenthesis r to the power of n minus 1 right parenthesis over denominator r minus 1 end fraction semicolon space r greater than 1 D a n space u n t u k space m e n c a r i space r a s i o space a d a l a h space r to the power of m minus n end exponent equals U subscript m over U subscript n M a k a semicolon r to the power of left parenthesis 6 minus 2 right parenthesis end exponent equals U subscript 6 over U subscript 2 equals fraction numerator 2.048 over denominator 8 end fraction r to the power of 4 equals 256 r equals 4 U subscript n equals a r to the power of n minus 1 end exponent a equals U subscript n over r to the power of n minus 1 end exponent equals U subscript 2 over r to the power of 2 minus 1 end exponent equals 8 over 4 equals 2 S e h i n g g a semicolon S subscript n equals fraction numerator a left parenthesis r to the power of n minus 1 right parenthesis over denominator r minus 1 end fraction semicolon space r greater than 1 S subscript 5 equals fraction numerator 2 left parenthesis 4 to the power of 5 minus 1 right parenthesis over denominator 4 minus 1 end fraction equals 2 over 3 left parenthesis 1.024 minus 1 right parenthesis equals 682 J u m l a h space 5 space s u k u space p e r t a m a n y a space y a i t u space 682.$