The domain of a function is the set of values of the independent variable for which the function is defined. The square root function is defined for all non-negative real numbers. So, ...
The domain of
y = √x
is all real numbers greater than or equal to zero. (x ≥ 0)
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In some cases, there may be other limits on the domain of a function. A function may be defined for all values of mass, for example, but is of no practical use for values of mass greater than the mass of the known universe (or planet Earth, perhaps).
