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Rational Expression

  • Thread starter Sparky_
  • Start date
  • #1
196
1

Homework Statement



I have volunteered to help a friend's son with his Algebra 2 (thinking - no problem, I've had Calc 1-3, differential equation, complex variables, probability / stats and so on.

So I start to help and the first questions:

Why aren't these rational expressions:
[tex]
\frac {\sqrt(x)}{(x+3)}
[/tex]

and


[tex]
\frac {\sqrt{(x-y)^2}}{(x)}
[/tex]



Homework Equations





The Attempt at a Solution




I know if the square root wasn't in the numerator they would be rational - at least I hope I'm correct.

I don't know why they aren't reational.

Thanks
-Sparky
 

Answers and Replies

  • #2
HallsofIvy
Science Advisor
Homework Helper
41,793
922
Yes, a "rational function" is defined as "a polynomial divided by a polynomial". What you give is not a rational function because [itex]\sqrt{x}[/itex] is not a polynomial.
 
  • #3
196
1
Ok - "polynomial divided by polynomial"

I was going to have to dig out my old algebra book. - in fact I probably still will have to dig it out to avoid embarassment.

Thanks so much!!!!
 

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