Question

how do I graph domains of several variables?
for example: D: {(x,y)lx+y>5}

Answer 1

In this case, draw the line x + y = 5 and then shade the region
where x + y > 5

Answer 2

That region is one of the halves of the plane on either side of
x + y = 5.

Hopefully it's clear to you which it is!

Answer 3

hold on!

Answer 4

like this?