xlog(x+15)-2.xlog10 +1 =0

jawab

ˣlog (x +15) - 2. ˣlog 10  + 1 = 0
ˣlog (x+15) -  ˣlog (10²) =  -1
ˣlog { (x+15)/100 } = ˣlog x⁻¹
(x + 15)/100 = 1/x
x(x+5) = 100
x² + 5x - 100 = 0
(x + 20)(x - 5) = 0
x = - 20  atau x = 5

pembatas ˣlog (x + 15)
x > 0 atau x + 15 > 0
x > 0 atau x > -15
x > 0

Hp  x = 5