Question

Tentukan nilai x yang memenuhi persamaan berikut!
A . Log (6x+8)=log (2x-4) + log 8
B . Log 2x - log4 = log32
C . Log (2x+2) - log (2x-2) = log6

Answer 1

A . Log (6x+8)=log (2x-4) + log 8
log (6x + 8 ) = log [(2x-4) x 8]
log (6x + 8 )  = log (16x - 32)
6x + 8 = 16x - 32
8 + 32 = 16x - 6x
40 = 10x
x = 4
B . Log 2x - log4 = log32
log (2x / 4) = log 32
2x / 4 = 32
2x = 32 . 4
x = 64

C . Log (2x+2) - log (2x-2) = log6
log [(2x+2)/(2x-2)] = log 6
[(2x+2)/(2x-2)] = 6
2x + 2 = 6 ( 2x - 2)
2x + 2 = 12x - 12
2 + 12 = 12x - 2x
14 = 10x
x = 1,4