Question

Nilai x yang memenuhi persamaan berbentuk 5log (x+5) + 5log (x-3) - 5log (x+15) = 0

Answer 1

5'log (x + 5) + 5'log (x - 3) - 5'log (x + 15) = 5'log 1
5'log (x + 5)(x - 3)/(x + 15) = 5'log 1
x² + 2x - 15 = x + 15
x² + x - 30 = 0
(x + 6)(x - 5) = 0
ambil x = 5