Education Technology

Precalculus: Two Models are Better than One

by Texas Instruments


  • Students will determine and analyze an exponential model for the data involving carbon dioxide in the atmosphere.
  • Students will develop an improved model for this data by using the residuals associated with the exponential regression function.


  • regression equation
  • residual
  • residual plot
  • SSE = sum of the squares of the residuals (errors)

About the Lesson

This lesson involves modeling the amount of carbon dioxide in the air over a 12-month period.
As a result, students will:

  • Analyze the shortcomings of an exponential regression function fitting the given data.
  • Find an improved model by adding the original exponential function to one fitting the data in the residual plot of the original function.