Jawaban:

Nomor 4

²log (x + 1) + ²log x - ²log (x + 3) = 0

²log [(x + 1)x] - ²log (x + 3) = ²log 1

²log (x² + x) - ²log (x + 3) = ²log 1

²log [(x² + x)/(x + 3)] = ²log 1

(x² + x)/(x + 3) = 1

x² + x = x + 3

x² + x - x = 3

x² = 3

x = ± √3

sehingga diperoleh nilai x nya ialah

x = -√3 atau x = √3

Nomor 5

log x + log (x + 15) = 2

log (x(x + 15)) = log 2

log (x² + 15x) = log 2

x² + 15x = 2

x(x + 15) = 2

sehingga diperoleh nilai x nya adalah

x = 2 atau x + 15 = 2

x = 2 atau x = -13

Nomor 6

log (log x) = log (3 - log x) + log 2

log (log x) = log ((3 - log x)2)

log x = 6 - 2 log x

log x + 2 log x = 6

log x + log x² = log 6

log (x(x²)) = log 6

log x³ = log 6

x³ = 6

x = (6)^(1/3)

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