If I enter the expression
into my graphing calculator and then ask it for the fractional (rational) equivalent it cannot do so. Since the number is irrational it displays the first few decimal digits:
However, if I enter the expression
into the same graphing calculator and then ask it for the fractional equivalent it displays:
But this second number I entered is clearly not rational either.
What's going on?
(In reply to solution
Incidentally I can only get TI-84 Plus Silver edition graphing calculators to do this. Not the TI-83 or 84+, just the more expensive Silver Edition.
Several of my students have other brands of non-graphing scientific calculator: TI-30, Casio, Sharp.
I tried this on all of the calculators that have a rationalize key and none of them made this error.
Add that to the criticism of the over-priced TI graphing calculators.
I'm just finding out this goes further than I thought:
You can actually fool the calculator with A+B√2 with many values of A,B even if it doesn't exceed 100.
Edited on May 29, 2015, 12:31 pm
Posted by Jer
on 2015-05-29 12:26:22