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Diketahui . Suku ke-12 adalah ...

Pertanyaan

Diketahui begin mathsize 14px style 3 to the power of 4 comma space 3 to the power of 6 comma space 3 to the power of 8 comma space 3 to the power of 10 comma space... end style. Suku ke-12 adalah ...

  1. begin mathsize 14px style 3 to the power of 28 end style 

  2. begin mathsize 14px style 3 to the power of 26 end style

  3. begin mathsize 14px style 3 to the power of 24 end style

  4. begin mathsize 14px style 3 to the power of 22 end style 

  5. begin mathsize 14px style 3 to the power of 20 end style

Pembahasan Soal:

Diketahui begin mathsize 14px style 3 to the power of 4 comma space 3 to the power of 6 comma space 3 to the power of 8 comma space 3 to the power of 10 comma space... end style merupakan barisan geometri.

Perhatikan perhitungan berikut ini.

Rasio dapat dengan:

begin mathsize 14px style r equals U subscript 2 over U subscript 1 equals 3 to the power of 6 over 3 to the power of 4 equals 3 to the power of 6 minus 4 end exponent equals 3 squared end style

Rumus suku ke-n barisan geometri:

begin mathsize 14px style U subscript n equals a r to the power of n minus 1 end exponent end style

maka

begin mathsize 14px style table attributes columnalign right center left columnspacing 0px end attributes row cell U subscript n end cell equals cell a r to the power of n minus 1 end exponent end cell row cell U subscript 12 end cell equals cell 3 to the power of 4 open parentheses 3 squared close parentheses to the power of 12 minus 1 end exponent end cell row blank equals cell 3 to the power of 4 open parentheses 3 squared close parentheses to the power of 11 end cell row blank equals cell 3 to the power of 4 open parentheses 3 to the power of 22 close parentheses end cell row blank equals cell 3 to the power of 4 plus 22 end exponent end cell row blank equals cell 3 to the power of 26 end cell end table end style

Jadi, suku ke-12 adalah begin mathsize 14px style 3 to the power of 26 end style.

Dengan demikian, jawaban yang tepat adalah B.

Pembahasan terverifikasi oleh Roboguru

Terakhir diupdate 20 Mei 2021

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