Nilai x yang memenuhi adalah ….

Pertanyaan

R. Diah

Master Teacher

Mahasiswa/Alumni Universitas Negeri Malang

Jawaban terverifikasi

Pembahasan

$begin mathsize 14px style table attributes columnalign right center left columnspacing 0px end attributes row cell log presubscript presuperscript 4 invisible function application open parentheses 7 x plus 2 close parentheses end cell equals cell negative 1 end cell row cell log presubscript presuperscript 4 invisible function application open parentheses 7 x plus 2 close parentheses end cell equals cell log presubscript presuperscript 4 invisible function application 4 to the power of negative 1 end exponent end cell row cell 7 x plus 2 end cell equals cell 4 to the power of negative 1 end exponent end cell row cell 7 x plus 2 end cell equals cell 1 fourth end cell row cell 7 x end cell equals cell 1 fourth minus 2 end cell row cell 7 x end cell equals cell fraction numerator 1 minus 8 over denominator 4 end fraction end cell row cell 7 x end cell equals cell negative 7 over 4 end cell row x equals cell negative 1 fourth end cell end table end style$

Ingat pula syarat numerus harus lebih besar dari 0. Sehingga,

begin mathsize 14px style table attributes columnalign right center left columnspacing 0px end attributes row cell 7 x plus 2 end cell greater than 0 row cell 7 x end cell greater than cell negative 2 end cell row x greater than cell negative 2 over 7 end cell end table end style

Perhatikan gambar garis bilangan berikut ini.

Karena nilai terletak di daerah himpunan penyelesaian syarat numerusnya maka memenuhi persamaan logaritma tesebut.