TITLE: Domain and Range
# !b2 Problem:
Find the Domain D and Range R for the function,
> f := (x,y) -> sqrt(x-y);

# !b3 Solution:
Clearly this function is defined where the square root
is defined, i.e. for all non negative real numbers.
!c0 D = {(x,y) : x >= y}
<p>
The range is the set of values that f(x,y) can take.
We have,
!c0 R = {z : z >= 0}
since f(x,y) is defined as the POSITIVE square root of (x-y).

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