I'm doing some exam revision and theres a few questions on finding the domain and range of functions of 2 variables. With a function of 1 variable I know that the domain and range is just finding the max and min x value, and the max and min y value. With a function of 2 variables I am confused however, what exactly does it mean to find the domain and range, and what is the method for doing so. Eg this question. h(x,y) = 1500 - 3x^2-5y^2 Domain = all real numbers in x,y Range = (-oo,1500) However I do not know the process for finding this out, mainly as I am confused to the definition of what range and domain actually is. Can someone help me out here? More with what domain and range mean, I'm sure the question is easy once I know this.