What is the domain of the function?

enter image source here

1 Answer
Apr 8, 2018

x(,)
y(,0)(0,)

Explanation:

Recall that the domain is the set of valid inputs to the function. In this case, it is the set of all pairs (x,y) that are valid inputs.

Also recall that, while you cannot take the square root of a negative number, you can take the cube root of a negative number. For example, 38=2. Thus, 3x is valid for any value of x.

Additionally, 3y is valid for all inputs of y, but our function f(x,y)=3x3y is undefined when y=0, due to division by zero.

Thus, our domain is x(,), y(,0)(0,).

Note: This can be more concisely written as D={(x,y)Z×Z:y0}.