Question

Bilangan Logaritma
○tentukan nilai X,jika nilai X bilangan real :
1. log 3 + log 4 = log 9x
2. log (x+1) - log (x-1) = log 3
3. log (x-3) + log (x+1) = log 5
4. log (x+6) = log x +log 3

Answer 1

1. log (3 × 4) = log 9x
log 12 = log 9x
maka: 12 = 9x
x = 12/9

2. log (x+1) - log (x-1) = log 3
log [(x+1) / (x-1)] = log 3
maka:
x + 1 / x - 1 = 3
x + 1 = 3 (x - 1)
x + 1 = 3x - 3
x - 3x = -3 - 1
- 2x = -4
x = 2

Untuk nomor 3 dan 4 coba dikerjakan sendiri berdasarakan ulasan di atas :)
semoga bermanfaat