Logarithm Equation

thebristolsound · #1 $Old$ November 6th, 2009, 09:07 PM

has the solution x=

Defunkt · #2 $Old$ November 6th, 2009, 09:17 PM

Quote:

Originally Posted by thebristolsound $View Post$

has the solution x=

Use the fact that $ln(a) - ln(b) = ln(\frac{a}{b})$

And: $e^{ln(a)} = a$

To find the solution.

Debsta · #3 $Old$ November 6th, 2009, 09:20 PM

Recall the rule lnA - lnB =ln(A/B). Apply that to LHS.
Then you'll have ln [(x+1)/(x-2)} = ln x
Drop the lns so that (x+1)/(x-2)=x
This becomes x+1 = x(x-2) which gives a quadratic and go from there.

Remember to check your answers from the quadratic in the ORIGINAL log equation. Reject answers which don't give pos values for x+1, x-2 or x as ln A is not defined for non-positive A valus.