Solution 10617: ERROR SINGULARITY Using the Equation Solver on the TI-85 and TI-86 When a Solution is Calculated Using the TI-89 Family.
Why do I get ERROR SINGULARITY when using the Equation Solver on my TI-85 or TI-86 although an answer is given on the TI-89 family?
"ERROR SINGULARITY" occurs when the SOLVER equation contains a singularity (a point at which the function is not defined).
The difference between the software on the TI-89 family, TI-92 family and Voyage™ 200 and the TI-85 and TI-86 is that they use different linear system solvers, which use a slightly different criteria for determining when a linear system is too poorly conditioned to solve accurately.
For more information regarding your Texas Instruments graphing calculator, please refer to the guidebooks section.