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solve for x, and PLEASE explain!!!

2006-12-13 17:44:07 · 7 answers · asked by jose u 1 in Science & Mathematics Mathematics

7 answers

take ln(x-1) to the other side it beomes + and + is equal to in * in ln..

ln 12= ln [(x-1)(x-2)]

12 = (x-1)(x-2)

solving x as a quadratic equation gives u the answer as 5 and -2

2006-12-13 17:58:23 · answer #1 · answered by Hellbound Angel 2 · 0 1

This action needs no explanation:

ln 12 = ln(x-2) + ln(x-1)

now, remember that ln ab = ln a + ln b ?

ln 12 = ln [(x-2)(x-1)]

12 = (x-2)(x-1), this is a quadratic,

but you can look at it and see how to solve 12 =4*3, so...

one solution is x =5. Ignore the negative solution.

2006-12-13 17:51:59 · answer #2 · answered by modulo_function 7 · 0 0

Using the laws of ln, ln(12)-ln(x-1) can be rewritten as ln(12/(x-1)).

Then take each side to e, so you get 12/(x-1)=x-2.

Then multiply each side by (x-1) to get 12=(x-2)(x-1).

After some expansion and such, you get 0=(x^2)-3x-10.

Using factorization, 0=(x+2)(x-5). Therefore, x=-2 and x=5. But, all ln have to be a non-negative number, therefore x=5.

2006-12-13 17:56:11 · answer #3 · answered by Anonymous · 0 0

ln(12/x-1)=ln(x-2)
12=x^2-3x+2
0=x^2-3-10
0=(x-5)(x+2)
x=5 bc u ignore the negative

2006-12-13 17:53:20 · answer #4 · answered by knolan8806 1 · 0 0

ln 12 = ln(x-2) + ln (x-1) = ln (x-2) (x-1)

go to exponential e^lnx = x

(x-2) (x-1) =12

x^2 -3x +2 =12

x^2 -3x -10 =0

roots are 5 and -2 which is impossible since there are no ln of negative numbers

ANSWER x = 5

2006-12-13 17:53:37 · answer #5 · answered by maussy 7 · 0 0

ln 12 - ln (x-1) = ln (x-2)
=> 12 / (x-1) = x-2
=> x^2 -3x -10 = 0
=> x^2 -5x +2x -10 = 0
=> x(x-5)+2(x-5) = 0
=> (x-5)(x+2)=0
x=5 OR x=-2

2006-12-13 19:04:21 · answer #6 · answered by yasiru89 6 · 0 0

right here's a sprint: the 1st 2 words are the two squared and have an analogous variable ln(x). for this reason, 3ln(x)^2 could be subtracted from 5ln(x)^2 providing you with the hot equation 2ln(x)^2+a million=0. i'm not sure if which will help or no longer, even though it a minimum of simplifies your equation slightly.

2016-10-05 07:17:35 · answer #7 · answered by ? 4 · 0 0

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