Finding the Solution for a Tricky ln Equation

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In summary, the conversation discusses how to solve the equation ln(x+1) = x-3, using the knowledge that ln is a logarithm with base e. It is mentioned that rearranging the equation using algebra leads to a dead end, and that a numerical solution may be necessary. It is also noted that there is no algebraic solution for this type of problem, which involves both a transcendental and non-transcendental function.
  • #1
dnt
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ln (x+1) = x-3

i know ln is log base e so the equation becomes:

e^(x-3) = x + 1

and i can rearrange using algebra to get:

e^x = e^3(x+1)

but now I am stuck...how can i separate the x's to solve for it?

thanks.
 
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  • #2
You can't write the solution x in terms of elementary functions like e^x and ln(x). You'll probably have to use a calculator to get an approximate numerical solution.
 
  • #3
ah thanks.
 
  • #4
In general, there is no "algebraic" solution for problems that involve both a transcendental function of x (such as ex) and non-transcendental function of x (such as x+1). You will have to use some approximation method (such as graphing y= ex-3 and y= x+1 and seeing where they cross).
 

Related to Finding the Solution for a Tricky ln Equation

1. What is a ln equation?

A ln equation is an equation that contains a natural logarithm function, written as ln(x), where x is the variable.

2. How do I solve a ln equation?

To solve a ln equation, you need to isolate the logarithm on one side of the equation and then take the inverse of the natural logarithm function to both sides. This will leave you with the value of the variable.

3. Can you give an example of solving a ln equation?

Sure! Let's say we have the equation ln(x) = 4. To solve for x, we would take the inverse of the natural logarithm function to both sides, giving us x = e^4. So the solution to this ln equation is x = 54.598.

4. What if there are other variables or constants in the ln equation?

If the ln equation contains other variables or constants, you would treat it the same way as a regular algebraic equation. You would simplify the equation and then solve for the variable using the rules of logarithms.

5. Is there a specific method for solving ln equations?

Yes, there are specific steps you can follow to solve ln equations. These include isolating the logarithm, taking the inverse of the natural logarithm, and simplifying the equation using logarithm rules. It's important to follow these steps carefully to ensure an accurate solution.

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