Brainlag Plus
Brainlag PlusRegions in depth
Describe and use regions on a graph when some boundaries are strict and some are not: dashed and solid lines, which side to shade, whole-number points in a region, the greatest value of an expression there, and boundaries you have to find yourself.
Dashed or solid
Every inequality in two variables has a boundary line. Draw it dashed for < or > (the points on the line are not included) and solid for ≤ or ≥ (they are). Reading a graph works the other way: a dashed edge means a strict inequality.
Read the question for the shading: usually the region R is shaded, but some questions ask you to leave R unshaded and shade the parts you do not want.
The rest of this lesson and its 8 practice questions are in Plus.
Screen 1 of 4, free to read.
- 8 exam-style questions, marked as you go, each with a worked solution
- Anything you get wrong is saved to your flashcards