Math 1 · Unit 5 · Lesson 1 · part 3 of 6
The edge rule: dashed or solid
One question is left: do the points on the line count?
The edge rule: dashed or solid
One question is left: do the points on the line count? The symbol decides, exactly as in Unit 1, Lesson 6.
Strict: < or >. Dashed line.
y > 2x + 1 says y is strictly bigger than the line's y. A point on the line has y exactly equal, so it does not count. Draw the boundary dashed, a dotted line that says: not this line, just past it.
Or-equal: ≤ or ≥. Solid line.
y ≥ 2x + 1 says y is bigger or equal. A point on the line has y exactly equal, so it counts. Draw the boundary solid: the edge is part of the region.
Is a point a solution?Put its x and y into the inequality and read the sentence. True: solution. False: not.
On the pictureA solution sits in the shaded region, or on the line when the line is solid.
The edge rule< and >: dashed, edge not included. ≤ and ≥: solid, edge included. Same as the open and closed circles from Unit 1.