# SOLUTION: Wasn't really sure if this problem belonged in this category, please excuse me if I'm asking in the wrong place. "Find all numbers for which the rational expression is undefined

Algebra ->  Algebra  -> Rational-functions -> SOLUTION: Wasn't really sure if this problem belonged in this category, please excuse me if I'm asking in the wrong place. "Find all numbers for which the rational expression is undefined      Log On

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 Algebra: Rational Functions, analyzing and graphing Solvers Lessons Answers archive Quiz In Depth

 Question 465762: Wasn't really sure if this problem belonged in this category, please excuse me if I'm asking in the wrong place. "Find all numbers for which the rational expression is undefined:" r^3-7r/r^2-64 Thanks for the help...Answer by solver91311(16877)   (Show Source): You can put this solution on YOUR website! I moved your question to the correct category. Rational functions are defined for all real numbers except those real numbers that would cause the denominator to equal zero. Note that there must be at least one instance of a variable in the denominator in order for the expression to qualify as a rational expression. Set the denominator expression equal to zero and solve the resulting equation. All roots of this equation are excluded from the domain of the rational function. In your case, since your denominator is a quadratic, and because the lead coefficient and the constant term have opposite signs, you have two real values that will satisfy the quadratic equation that results when you set the denominator equal to zero. Those two numbers will cause the rational expression to be undefined. John My calculator said it, I believe it, that settles it