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Pertanyaan

Akar-akar dari 12 ( 2 lo g x ​ ) + 2 lo g x 1 ​ = 5 adalah x 1 ​ dan x 2 ​ . Nilai x 1 6 ​ + x 2 6 ​ = ...

Akar-akar dari  adalah . Nilai

  1. 12 space

  2. 16 space

  3. 24 space

  4. 30 space

  5. 32 space

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M. Nasrullah

Master Teacher

Mahasiswa/Alumni Universitas Negeri Makassar

Jawaban terverifikasi

Jawaban

jawaban yang tepat adalah A

jawaban yang tepat adalah A

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Pembahasan

Ingat kembali: Misalkan: Sehingga diperoleh perhitungan: Untuk Untuk Sehingga, Dengan demikian, nilai adalah Jadi, jawaban yang tepat adalah A

Ingat kembali:

a to the power of n equals stack stack a cross times a cross times a cross times... cross times a with underbrace below with a space s e b a n y a k space n below comma space a not equal to 0

log presuperscript a space a to the power of n equals n comma space a greater than 0

log presuperscript a space b to the power of n equals n log presuperscript a space b space comma space a space dan space b greater than 0

log presuperscript a space f open parentheses x close parentheses equals log presuperscript a space g open parentheses x close parentheses rightwards arrow f open parentheses x close parentheses equals g open parentheses x close parentheses 

open parentheses a to the power of m close parentheses to the power of n equals a to the power of m times n end exponent comma space a not equal to 0

Misalkan:

log presuperscript 2 space x equals a

Sehingga diperoleh perhitungan:

table attributes columnalign right center left columnspacing 0px end attributes row cell 12 open parentheses log presuperscript 2 space square root of x close parentheses plus fraction numerator 1 over denominator log presuperscript 2 space x end fraction end cell equals 5 row cell 12 open parentheses log presuperscript 2 space x to the power of 1 half end exponent close parentheses plus fraction numerator 1 over denominator log presuperscript 2 space x end fraction minus 5 end cell equals 0 row cell 12 times 1 half open parentheses log presuperscript 2 space x close parentheses plus fraction numerator 1 over denominator log presuperscript 2 space x end fraction minus 5 end cell equals 0 row cell 6 open parentheses log presuperscript 2 space x close parentheses plus fraction numerator 1 over denominator log presuperscript 2 space x end fraction minus 5 end cell equals 0 row cell 6 straight a plus 1 over straight a minus 5 end cell equals cell 0 space open parentheses sama minus sama space dikali space straight a close parentheses end cell row cell straight a open parentheses 6 straight a close parentheses plus straight a open parentheses 1 over straight a close parentheses minus straight a open parentheses 5 close parentheses end cell equals 0 row cell 6 straight a squared plus 1 minus 5 straight a end cell equals 0 row cell 6 straight a squared minus 5 straight a plus 1 end cell equals cell 0 space open parentheses difaktorkan close parentheses end cell row cell open parentheses 3 straight a minus 1 close parentheses open parentheses 2 straight a minus 1 close parentheses end cell equals 0 row blank blank cell straight a equals 1 third space atau space straight a equals 1 half end cell end table    

Untuk a equals 1 third 

table attributes columnalign right center left columnspacing 0px end attributes row cell log presuperscript 2 space x end cell equals a row cell log presuperscript 2 space x end cell equals cell 1 third end cell row cell log presuperscript 2 space x end cell equals cell log presuperscript 2 space 2 to the power of 1 third end exponent end cell row cell x subscript 1 end cell equals cell 2 to the power of 1 third end exponent end cell end table  

Untuk a equals 1 half 

  table attributes columnalign right center left columnspacing 0px end attributes row cell log presuperscript 2 space x end cell equals a row cell log presuperscript 2 space x end cell equals cell 1 half end cell row cell log presuperscript 2 space x end cell equals cell log presuperscript 2 space 2 to the power of 1 half end exponent end cell row cell x subscript 2 end cell equals cell 2 to the power of 1 half end exponent end cell end table 

Sehingga,

table attributes columnalign right center left columnspacing 0px end attributes row cell x subscript 1 to the power of 6 plus straight x subscript 2 to the power of 6 end cell equals cell open parentheses 2 to the power of 1 third end exponent close parentheses to the power of 6 plus open parentheses 2 to the power of 1 half end exponent close parentheses to the power of 6 end cell row blank equals cell 2 to the power of 1 third times 6 end exponent plus 2 to the power of 1 half times 6 end exponent end cell row blank equals cell 2 squared plus 2 cubed end cell row blank equals cell 4 plus 8 end cell row blank equals 12 end table  

Dengan demikian, nilai x subscript 1 to the power of 6 plus x subscript 2 to the power of 6  adalah 12

Jadi, jawaban yang tepat adalah A

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