Refer to the following plot of some level curves of  f(x, y) = c for c = −2, 0, 2, 4, and 6.  (Each grid square is 1 unit ✕ 1 unit.) The x y-coordinate plane is given. There are five level curves. The level curve labeled −2 consists of two loops, the first in the second quadrant and the second in the fourth quadrant, and this level curve passes through the points (−2, 1.5), (−2, 3), (−3, 2), (2, −1.5), (2, −3), and (3, −2). The level curve labeled 0 consists of two loops, the first in the second quadrant and the second in the fourth quadrant, and this level curve passes through the points (−1, 1), (−1, 3.5), (−2, 0.5), (−2, 3.5), (−3, 0.5), (−3, 3), (1, −1), (1, −3.5), (2, −0.5), (2, −3.5), (3, −0.5), and (3, −3). The level curve labeled 2 consists of the x‐ and y‐axes. The level curve labeled 4 consists of two loops, the first in the first quadrant and the second in the third quadrant, and this level curve passes through the points (1, 1), (1, 3.5), (2, 0.5), (2, 3.5), (3, 0.5), (3, 3), (−1, −1), (−1, −3.5), (−2, −0.5), (−2, −3.5), (−3, −0.5), and (−3, −3). The level curve labeled 6 consists of two loops, the first in the first quadrant and the second in the third quadrant, and this level curve passes through the points (2, 1.5), (2, 3), (3, 2), (−2, −1.5), (−2, −3), and (−3, −2). At approximately which point or points does f appear to attain a maximum value?

In simple mathematics terms, a domain is defined as the space on which all the possible inputs for the function will lie. It can also be expressed as a set of departures for the required function.