From: Pat Ballew (for Teacher2Teacher Service)
Date: May 08, 2000 at 18:06:17
Subject: Re: Dividing by zero

I am not sure what the exact question is, but it seems that two things are
being confused here... 

1)  If we ask for the solution to a problem that does
not have a solution (solve x=x+3) we often say the solution set is the null
set or empty set (this goes back to the reform after sputnik when all
solutions were written as sets and most problems were written in set
theoretic notation).  When we ask for the evaluation of a function and the
point where it is not continuous, we do not normally use any such language.
We may say the function is not defined at that point.

Contrast for the student that in one case we are evaluating an expression
(and can not) and in the other we are solving an equation (and can not).

I hope this helps, certainly it is hard for students to sort out some of the
language, especially when it is not always consistent, but this is one of
those places where the fine art of keeping separate things separate should be
emphasized.

 -Pat Ballew, for the Teacher2Teacher service

Visit us again at http://mathforum.com/t2t/

Post a public discussion message
Ask Teacher2Teacher a new question