Education Technology

Algebra II: What is Log?

by Texas Instruments


  • Students will recognize the function g(x) =  logx(x) as the inverse of f(x)=bx where b > 0 and b ≠ 1
  • Students will apply this inverse relationship and solve simple logarithmic equations


  • Exponential function
  • Logarithmic function
  • One-to-one function
  • Inverse function
  • Domain and range

About the Lesson

This lesson involves the one-to-one function f(x)=bx. In acknowledging the existence of its inverse, students will:

  • Use the domain and range of f(x) to determine the domain and range of f-1(x).
  • Interpret the graph of f-1(x) as the reflection of f(x) across the line y = x.
  • Use this inverse relationship to write an equation for the graph of the inverse.
  • Recognize the logarithmic notation needed to define the inverse function.
  • Use the inputs and outputs of two inverse functions to complete a table.

    As a result, students will:
  • Solve simple logarithmic equations and verify solutions using the corresponding exponential equations.