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Study Guides > College Algebra CoRequisite Course

Summary: Review

Key Concepts

  • Division by [latex]0[/latex] is undefined.
  • Values of the input variable that would make the denominator of a rational expression equal to zero must be stated and excluded from the domain of a function containing the expression.
  • To restrict the domain of a rational function, set the denominators each equal to zero. Solve for the variable in each denominator and exclude those solution sets.
  • Taking an even root (e.g., a square root) of a negative number yields an unreal result.
    • Values of the input variable that would place a negative amount under an even root must be stated and excluded from the domain of a function containing the expression.
  • To restrict the domain of a function containing one radical, set the radicand greater than or equal to zero. Solve for the variable. The resulting solution set is the domain of the function.
  • The domain of a function is read from the x-axis (the horizontal, or independent, axis) of the graph of the function.
  • The range of a function is read from the y-axis (the vertical, or dependent axis) of the graph of the function.

Glossary

domain
the set of all possible input into a function
radical function 
a function containing a radical
radicand 
the value underneath the radical sign
range
the set of all possible output from a function
rational function 
a function containing a rational expression (a fraction)

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