anyone know how to solve this? the answer is 8
Ln(2x+5)-Ln3=Ln(x-1)
2007-12-17 20:12:06 · 5 answers · asked by Molina88 2 in Science & Mathematics ➔ Mathematics
Ln(2x+5)-Ln3=Ln(x-1)
Ln(2x+5)/3 = Ln(x-1)
(2x+5)/3 = (x-1)
(2x+5)=3(x-1)
2x+5=3x-3
x=8
Best of Luck !!
2007-12-17 20:17:18 · answer #1 · answered by Murtaza 6 · 2⤊ 2⤋
Ln(2x+5)-Ln3 = Ln(x-1) (bring the Ln x's to one side).
Ln(2x+5) - Ln(x-1) = Ln(3) (minus becomes division when you take away the log).
Ln(2x+5 / x-1) = Ln(3). (take anti-logs).
(2x+5)/(x-1) = 3
(2x+5)=3(x-1)
2x+5=3x-3
5+3 = 3x-2x
8 = x
2007-12-17 21:02:21 · answer #2 · answered by Sparks 6 · 0⤊ 2⤋
when using logs, subtractino = division after you take out the ln or log signs
so do (2x+5)/3 = (x-1)
then solve for x and u get 8
2007-12-17 20:17:43 · answer #3 · answered by swtgirl988 2 · 0⤊ 2⤋
ln [ (2x + 5) / 3 ] = ln (x - 1)
(2x + 5) / 3 = x - 1
2x + 5 = 3x - 3
x = 8
2007-12-17 22:09:14 · answer #4 · answered by Como 7 · 3⤊ 1⤋
You first need to know ln(a)-ln(b)=ln(a/b)
In the LHS,
ln[(2x+5)/3]=ln(x-1)
2x+5=3x-3
x=8
You are right
2007-12-17 21:27:30 · answer #5 · answered by someone else 7 · 0⤊ 1⤋