Solution 38156: TI-Nspire CX Family Max/Min function in Graphs and Geometry may give Incorrect Answers when using Function defined in terms of a Derivative of an Exponential Function.
Why does the TI-Nspire CX Family Max/Min function in Graphs and Geometry give incorrect answers when using a function defined in terms of a derivative of an exponential function?
TI-Nspire CX Family Max/Min function in Graphs and Geometry give incorrect answers when using a function defined in terms of a derivative of an exponential function because of an issue identified by our development team. However, this issue has been resolved in TI-Nspire CX Version 4.5 software.
The issue can be circumvented by explicitly entering the derivative in the edit line rather than entering derivative(f(x),x); in other words, calculate the derivative (in Calculator if using CAS or by hand if no access to a CAS) and enter that calculation into the Graphs and Geometry edit line. The correct max and min values will be returned. Also, the min/max values can be computed in a Calculator page. The user can define fp(x) in a Calculator page and then enter nfMax(fp(x),x,lowerBound,upperBound) and the same format for nfMin. This can be done on TI-Nspire CX CAS or TI-Nspire CX numeric software.
If you have questions about the information listed above, please contact TI-Cares for additional assistance.