Answer: 13.
- A 9
- B 13
- C 25
- D 5
Correct answer: B. 13
Explanation: Counting lattice points in the diamond gives 1 + 4 + 8 = 13.
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.