Rational Expressions

Discussion in 'Algebra' started by nycmathguy, Aug 5, 2022.

  1. nycmathguy

    nycmathguy

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    College Algebra
    Chapter 1/Section 7

    The quotient of two polynomial functions is called a rational expression.

    If f(x) and g(x) are polynomial functions, then
    f(x)/g(x) is a rational expression. A rational expression is a fraction..

    If f(x) = x/(x - 1), then f(x) is a rational expression in one variable.

    If g(x) = (xy)^2/(x - y)^3, then g(x) is a rational expression in two variables.

    Is any of this right?

    Question

    Is there such a thing as a rational expression in more than two variables? If so, can you give two examples?

    Thank you.
     
    nycmathguy, Aug 5, 2022
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  2. nycmathguy

    MathLover1

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    you are confusing expressions with functions
    f(x) = x/(x - 1), then f(x) is a rational function

    x/(x - 1) is an expression

    same for g(x)

    a rational expression in more than two variables: (xyz^2)/(5x^2y^3z^-1)
     
    MathLover1, Aug 5, 2022
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  3. nycmathguy

    nycmathguy

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    What am I confuses about? A rational expression is simply one polynomial divided by another. No?
     
    nycmathguy, Aug 5, 2022
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  4. nycmathguy

    MathLover1

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    yes, rational expression is simply one polynomial divided by another

    but you say f(x) = x/(x - 1) is a rational expression, which is not; it is a rational function
     
    MathLover1, Aug 5, 2022
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    nycmathguy likes this.
  5. nycmathguy

    nycmathguy

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    So, x/(x - 1) is a rational expression.

    f(x) = x/(x - 1) is a rational function.

    The difference is one contains f(x) = and the other does not.
     
    nycmathguy, Aug 5, 2022
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