# I Logarithm Problem

#### Gurasees

How to solve "ln(a/b+1)" after applying the identity "ln(a+b)=ln b + ln(a/b+1)" ?
where "ln" is natural log, a and b have variable values in them.

#### Attachments

• 290.2 KB Views: 123
Last edited:

#### fresh_42

Mentor
2018 Award
What do you mean by "solve"?

#### Gurasees

What do you mean by "solve"?
The identity keeps repeating itself in the solution,
I want to take ln of

• {e^(-6.7/(T-292)) + 0.56/(T-292)} / {3/(T-292)}

#### Attachments

• 290.2 KB Views: 87

#### fresh_42

Mentor
2018 Award
So you have $\log \left( (T-292)\exp\left( \dfrac{-6.7}{T-292} \right) + 0.56 \right) - \log(3)\,.$
I think you can only solve this numerically, resp. expand the exponential function and the logarithm into power series, in which case you must consider the interval of convergence.

#### Gurasees

So you have $\log \left( (T-292)\exp\left( \dfrac{-6.7}{T-292} \right) + 0.56 \right) - \log(3)\,.$
I think you can only solve this numerically, resp. expand the exponential function and the logarithm into power series, in which case you must consider the interval of convergence.
I don't know how to do that. Can you send me some links which might be helpful for the solution?

#### fresh_42

Mentor
2018 Award
I don't know how to do that. Can you send me some links which might be helpful for the solution?
Solution of what? You cannot simplify this expression further. To solve something, an equation would be helpful. You can find the power series on Wikipedia if you look for the exponential, resp. logarithmic function. But look out for the range of $T-292\,.$

#### mfb

Mentor
I still don't see an equation you could solve. Can you "solve a+b"?
We have an expression that depends on T. Should that be equal to something specific? Do you want to find a T such that the expression will obtain a given value? That will need numerical approximations.

#### Gurasees

Solution of what? You cannot simplify this expression further. To solve something, an equation would be helpful. You can find the power series on Wikipedia if you look for the exponential, resp. logarithmic function. But look out for the range of $T-292\,.$
Solution of what? You cannot simplify this expression further. To solve something, an equation would be helpful. You can find the power series on Wikipedia if you look for the exponential, resp. logarithmic function. But look out for the range of $T-292\,.$

#### Gurasees

Solution of what? You cannot simplify this expression further. To solve something, an equation would be helpful. You can find the power series on Wikipedia if you look for the exponential, resp. logarithmic function. But look out for the range of $T-292\,.$
I can't find the expansion of ln(x-a). Can you help?

#### fresh_42

Mentor
2018 Award

"Logarithm Problem"

### Physics Forums Values

We Value Quality
• Topics based on mainstream science
• Proper English grammar and spelling
We Value Civility
• Positive and compassionate attitudes
• Patience while debating
We Value Productivity
• Disciplined to remain on-topic
• Recognition of own weaknesses
• Solo and co-op problem solving