CHANGE OF BASE FORMULA FOR LOGARITHMS
  • This worksheet allows you to play with the Change of Base Formula for Logarithms:   $$ \log_b\,x = \frac{\log_a\,x}{\log_b\,a} $$
  • Click anywhere in the GeoGebra window (at right) to make it active.
  • Use the sliders to change:
    • the base of the starting logarithm,
      original base’:   $$ \log_{\LARGE \color{green}b}\,x = \frac{\log_a\,x}{\log_{\LARGE \color{green}b}\,a} $$
    • the base that you want to change to,
      new base’:   $$ \log_{b}\,x = \frac{\log_{\LARGE \color{green}a}\,x}{\log_{b}\,{\LARGE \color{green}a}} $$
    • the input to the logarithm,
      input to logarithm’:   $$ \log_{b}\,{\LARGE \color{green}x} = \frac{\log_{a}\,{\LARGE \color{green}x}}{\log_{b}\,{a}} $$
  • Refresh this page at any time to restore it to its initial configuration.
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Dr. Carol J.V. Fisher, August 16, 2007, Created with GeoGebra