Has anyone ever heard of finding the excluded values for x?
Which chapter would this be in, if it were in the book, there are about 8 chapter in the algebra book and it isn't in there anywhere, the teacher is teaching this topic and it would be nice to know which category this would fall under in elementary algebra ? What do you think , we have these chapters: 1. Basic notation
2.Algebraic expressions
3.First degree equations and inequalities
4.Rational expressions
5.Graphing straight lines
6.Graphs and systems of linear equations
7. Exponents and polynomials
8.Factoring
9. Radicals
10. Quadratic equations
I think it would only make sense somewhere between rational expressions and graphing. When you're asked to "find excluded values for x," those are the values that would make a rational expression undefined (and therefore cause a break in the graph).
For example, take the rational expression x²/(x-2).
If we let x equal 2, the entire denominator would equal zero— but of course division by zero is not allowed (it's "undefined"). So when you graph this, there will be a break in the graph at x=2.
You can graph it here to see what I mean (type in "(x^2)/(x-2)" and then zoom out): http://www.coolmath.com/graphit/
...
BTW, I'd say this is actually a little beyond elementary algebra. Finding excluded values for x is really a pre-calculus subject.
Beg Algebra: Introduction to Inequalities
