Answer: included.
- A included
- B excluded
- C at infinity
- D undefined
Correct answer: A. included
Explanation: A filled circle means the endpoint value is part of the solution set (≤ or ≥).
One-variable inequalities use open (excluded) or closed (included) circles on a number line; two-variable inequalities use a dashed (strict) or solid (non-strict) boundary line, with the solution being the entire shaded half-plane on one side of it.
Concept context
Solving linear inequalities in one and two variables algebraically and graphically, and representing solutions on a number line or as a region in a plane.