TI89 titanium logarithms

  • Calculators
  • Thread starter calypsob
  • Start date
  • #1
2
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Main Question or Discussion Point

First of all I would like to share this because I randomly found it and I commonly see that people approach base changes of common logs on the ti89 titanium in a very different way.
Scroll half way down page 2 http://education.ti.com/xchange/AUS-NZ/Mathematics/Number/12250/SomehelpQAontheTI89.pdf [Broken]
Also, the command "Diamond" and then 7 opens the log() function on ti89 titanium

Ok on to my question.

is there a quick way to enter this equation and simplify?

5lnx+6lny-4lnz =

The answer is ln(x^5*y^6/z^4)
 
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Answers and Replies

  • #2
5
2
You lose some accuracy if you use complex numbers, but one easy way is to do ln(e^(5 ln x + 6 ln y - 4 ln z)). Use diamond-x for e^, or CHAR-MATH-5 also gives you the correct e.

This is just a simple algebra trick: ln(e^x)) = x, but the calculator doesn't try to simplify anymore. If you do e^ln(x), your domain is limited to positive numbers, and the calculator changes the format again.
 

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