# Math Help - Does TI-89 Titanium Make a Mistake

1. ## Does TI-89 Titanium Make a Mistake

I have calculated the inequality (1-x^2)/(x^2-3x+2)>0 and the result was -1<x<2 But if x is 1 then the denominator and the numerator are both zero. X=1 does not satisfy the equation however it is in the solution set. Should I get another calculator because this is a pretty easy operation to do for TI 89 and it should not fail in my opinion. Can someone inform me about this topic and I also want to know if anyone has experienced similar problems with a calculator from TI. I have also included screen captures.
Thanks in advance for help.

2. In your example, the num and denom can be factored and cancel a (x-1) term. So perhaps the calculator is simply automatically doing this. That's a great calculator, NO need to get another right now.

3. I have downloaded another OS for the calculator and it now simplifies the equation to (x+1)/(x-2)<0 at the cost of losing every program. So you are right it cancels the x-1 term but there must be a way to avoid canceling cause it is wrong to do so .

4. Is reverting to the OS before update possible somehow ?