## Thomas' Calculus 13th Edition

a. Domain : The set of all $(x,y)$ lie in the xy -plane. b. Range: It refers to all Real numbers c. Level Curves: The level curves are the hyperbolas along x- axis and y-axis refers to as asymptotes when $f(x,y) \ne 0$ as well as when $f(x,y)=0$ d. No Boundary points e. Both open and Closed f. Unbounded