# Knowledge Base

## Solution 12660: Equations Used to Calculate Linear Regressions on TI Graphing Calculators.

### What equations are used to calculate linear regressions on TI graphing calculators?

Typically, math classes use the form ax+b or mx+b (this ties into how polynomials are presented: ax2+bx+c). However, statistics classes often use the form a+bx. The TI-81 and the TI-85 use the form typically used in statistics classes, a+bx.

The TI-80, TI-82, TI-83 Plus Family, TI-84 Plus Family, TI-Nspire™ Family, and TI-Nspire™ CAS offer linear regression in both forms. The TI-89 family, TI-92 family, and Voyage™ 200 family graphing calculators use only the ax+b form.
Texas Instruments' feedback received from mathematics educators who were using the regression functions found that the educators wanted a form of the regression equation that tied into what was being used in the classroom. They found that mapping from the a+bx form to the ax+b form was a burden on their students, especially the introductory level students.

NOTE: The TI-Nspire family offers linear regressions using either the mx+b or a+bx equation.