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Solving Exponential Equations using Logarithms

To solve an exponential equation:

     1 ) Isolate the exponential expression.

     2 ) Take the logarithms of both sides.

     3 ) Solve for the variable .

  

Example 1:

Solve for x : 2 x = 12

      log 2 x = log 12 x log 2 = log 12 x = log 12 log 2 3.585

Example 2:

Solve for x : 8 ( 10 x ) = 12

      10 x = 12 8 = 3 2 log 10 x = log 3 2 x log 10 = log 3 2 x = log 3 2 0.176

Example 3:

Solve for x : e 5 x = 30

      ln e 5 x = ln 30 5 x ln e = ln 30 5 x = ln 30 x = ln 30 5 0.680