Solve Log Equation: Find Value of x

  • Thread starter kukki1990
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    Logarithmic
In summary, the conversation is about finding the value of x using logarithmic equations. The person attempted to solve it using log rules and obtained a cubic equation, but the correct answer is a quadratic equation. They are asking for help in finding where they went wrong in their solution.
  • #1
kukki1990
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Homework Statement


Find the value of x


Homework Equations


log x - 1/2log(x-1/2) = log(x+1/2) - 1/2log(x+1/8)


The Attempt at a Solution


used the log a + log b = log a*b & log a - log b = loga/b

and got a cubic equation 4x^3-8x^2-4x-1 = 0

but the answer in the book is x=1
 
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  • #2
Could you please show your steps on how you've obtained that polynomial?
 
  • #3
You should be getting a quadratic ([itex]3x^2-2x-1=0[/itex]) which will give you the correct answer. However, I can't tell you where you are going wrong until you show me your workings...
 

1. What is a logarithmic equation?

A logarithmic equation is an equation that contains a logarithm. A logarithm is the inverse function of an exponential function, meaning that it 'undoes' the effect of an exponential function. In other words, it helps us find the exponent that was used to raise a base number to a certain power.

2. How do I solve a logarithmic equation?

To solve a logarithmic equation, you can first rewrite it in exponential form. Then, isolate the logarithmic term on one side of the equation and the exponential term on the other side. Finally, solve for the variable by using the properties of logarithms or by using algebraic methods.

3. Can a logarithmic equation have multiple solutions?

Yes, a logarithmic equation can have multiple solutions. This is because a logarithm is not a one-to-one function, meaning that different inputs can result in the same output. It is important to check your solutions by plugging them back into the original equation to ensure they are valid.

4. What are the common bases used in logarithms?

The two most common bases used in logarithms are base 10 (written as log10) and base e (written as ln). The base 10 logarithm is used in many real-life applications, while the base e logarithm is commonly used in mathematical and scientific calculations.

5. How do I use a calculator to solve a logarithmic equation?

Most scientific calculators have a button for logarithms, usually labeled as 'log' or 'ln'. To find the value of x in a logarithmic equation, simply input the base and the result of the exponential term, and the calculator will give you the value of x. Make sure to use the correct base for your equation.

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