Chapter 1 - Section 1.9 - The Coordinate Plane; Graphs of Equations; Circles - 1.9 Exercises - Page 102: 16

See the image below

(a) We have to sketch region with only one restriction $y<3$. So the region covers any point below $y=3$ line. Note, we have strict inequality, so the $y=3$ line itself doesn't count. Also see the image above. (b) In this case we have a restriction, where $x=-4$. So for any $y$ value we need $x$ to be equal to $-4$. Visual representation of it will be a line $x=-4$ Also see the image above.