Posted by **Laura Grace** on Wednesday, March 23, 2011 at 9:55pm.

Solve the lograthmic function:

ln(X+5) = ln(X-1) - ln(X+1)

The answer has no solution but I do not know how to come to that answer. Help is greatly appreciated!

- pre calc -
**Reiny**, Wednesday, March 23, 2011 at 10:06pm
ln(x+5) = ln[(x-1)/(x+1)]

x+5 = (x-1)/(x+1)

(x+5)(x+1) = x-1

x^2 + 6x + 5 = x-1

x^2 + 5x + 6 = 0

(x+2)(x+3) = 0

x = -2 or x=-3

but in ln(x-1), x-1>0 or x > 1

remember we can't take the log of a negative number and we would get ln(-3) and ln(-4) which would be undefined.

so neither of the solutions are valid, and

there is no solution to your equation.

- pre calc -
**Laura Grace**, Thursday, March 24, 2011 at 8:44pm
Thank you soo much!

## Answer this Question

## Related Questions

- Math - Two-Step Inequalities - Please Help - I need help with this one, please. ...
- Math - How do you solve this? I have tryed so many times and can not get the ...
- Derivatives - Find the derivatives of: 1. H(x)= sin2xcos2x The answer given is ...
- Trig/Pre-Calc - Could someone please help me on this problem. I'm really ...
- Algebra - Simplifying y^2 + 3 + 3(y^2+1) My answer is 4y^2+6 but the program I ...
- PRE CALC - Use matrices to solve the system. (If the system has infinitely many ...
- Pre-Calc - √(X+10) + √(X-6) = 8 Help would be greatly appreciated! ...
- trig - How would I solve the following equation for x? 2 sin^2(x) + 3 tanx secx...
- Math - How do you solve this equation? The answer is suppose to be -0.7 Thanx ...
- Precalculus - Solve the equation x^3 - 2x + 4 = 0. ==> I know the answer is -...