# domain of a function

• October 25th 2009, 03:56 AM
yen yen
domain of a function
f(x;y) = 1/ (9x^2 + y^2)

what is the domain of this function? i know that 9x^2 + y^2 cannot be equals to 0 so where do i go from there?
• October 25th 2009, 04:00 AM
mr fantastic
Quote:

Originally Posted by yen yen
f(x;y) = 1/ (9x^2 + y^2)

what is the domain of this function? i know that 9x^2 + y^2 cannot be equals to 0 so where do i go from there?

The domain is the set of all ordered pairs (x, y) where $x \in$ R\{0} and $y \in$ R\{0}.
• October 25th 2009, 05:19 AM
Raoh
hi(Happy)
$9x^{2}+y^{2}$ cannot equal zero only when $x$ and $y$ aren't equal to zero.