I finally found out how all of you were getting the false statement when finding limits.  If you author the expression y = f(x) and ask to find a limit then you will get a false statement.  However, if you just enter the expression for f(x) without the "y = "  then you will be able to find the limit.

I was unable to duplicate the problem that I encountered with  sec ² (t-1)  that we had yesterday.  In fact, it worked perfectly for me when I tried it in my office to day.  I must have had something entered incorrectly. I'll keep on experimenting and let you know what I find out.

                             --CFW