Expert: Scott A Wilson - 9/24/2009

Question
How do you find the domain of a function? Please keep in mind that I'm only in Algebra and complex answers would only make my head hurt.

Thanks!

Laura.

Answer
The domain is all x that can be put in the function.

Examples:
y = x²; domain is all x, or (-∞,∞).

y = √(x+1); domain is all x >= -1,
    for the squareroot of a negative can't be done and x = -1 makes y = √(-1+1) = √0 = 0.

y = 5x² + 4/(x-1); the domain of x² is all x, but with (x-1) in the denominator,
    x-1 can't be 0, so with x-1 <> 0, x <> 1, so x can't be 1.

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Additional information:

The range is a whole other story, for the range is the y values produced
when all of the domain in x is looked at.