A. Log x + log ( x + 15 ) = 2

Bab Logaritma
Matematika SMA Kelas X

log x + log (x + 15) = 2
log (x (x + 15)) = 2
x² + 15x = 10²
x² + 15x = 100
x² + 15x - 100 = 0
(x + 20) (x - 5) = 0
x + 20 = 0
x = -20

x - 5 = 0
x = 5

syarat
x > 0

HP = { 5 }