Quandaries and Queries
  

 

Caitlyn
grade 11 pre-calculus
 
problem:  ln x + ln (x-2) = 1
 
I can solve this on the calculator, but the book wants 1+ [(sqroot)1+e].  How can I get the e? 
 
OR
 
problem:  ln x + ln (x^2 + 1) = 8
 

 

Hi Caitlyn,

You need to use the property of the log function that is

ln(a b) = ln a + ln b

Hence ln x + ln (x-2) = 1 becomes

ln(x(x - 2)) = 1

Now raise both sides to the power of e to get

 eln(x(x - 2)) = e1
x(x - 2) = e

This you can solve using the general quadratic.

Penny

 
 

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