What is the domain and range of f(x,y) = sqrt(9-x^2-y^2)f(x,y)=9x2y2?

1 Answer

Because f(x,y)=sqrt(9-x^2-y^2)f(x,y)=9x2y2 we must have that

9-x^2-y^2>=0=>9>=x^2+y^2=>3^2>=x^2+y^29x2y209x2+y232x2+y2

The domain of f(x,y)f(x,y) is the border and the interior of the circle
x^2+y^2=3^2x2+y2=32
or

The domain is represented by the disc whose center is the origin of the coordinates system and the radius is 3.

Now hence f(x,y)>=0f(x,y)0 and f(x,y)<=3f(x,y)3 we find that the range of the function is the interval [0,3][0,3]