SOLUTION: log(x+2) - log(2x+1)= logx I am not sure what to do with the (-) and how it effects the rest of the problem.

Algebra ->  Exponential-and-logarithmic-functions -> SOLUTION: log(x+2) - log(2x+1)= logx I am not sure what to do with the (-) and how it effects the rest of the problem.       Log On


   



Question 59793: log(x+2) - log(2x+1)= logx
I am not sure what to do with the (-) and how it effects the rest of the problem.

Answer by ankor@dixie-net.com(22740) About Me  (Show Source):
You can put this solution on YOUR website!
log(x+2) - log(2x+1)= logx
I am not sure what to do with the (-) and how it effects the rest of the problem.
:
Remember, that when you subtract exponents (or logs) it is the same as dividing
We could write the problem:
log[%28x%2B2%29%2F%282x%2B1%29] = log(x)
:
When the log of one expression = the log of another expression, the expressions are equal
%28x%2B2%29%2F%282x%2B2%29 = x
Cross mult
:
x(2x+1) = x + 2
:
2x^2 + x = x + 2
:
Subtract x from both sides
2x^2 = 2
:
x^2 = 2/2
:
x^2 = 1
:
x = 1
:
:
Check by substitution:
log(1 + 2) - log(2 + 1) = log(1)
log(3) - log(3) = 0
What is the log of 1? It's 0, right?