Module 2 · Algebra Foundations
Chapter 8: Linear Inequalities
Algebra
4 topics
What this chapter covers
The 4 topics below make up Linear Inequalities on the Digital SAT. Click any topic to open its notes, examples and practice test.
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Formula Reference Sheet
This chapter
Solving rules
| Same as equations | add/subtract/multiply/divide both sides |
|---|---|
| Flip rule | multiplying or dividing by a negative reverses the inequality |
| Symbols | < ≤ > ≥ |
Notation
| Open interval | (a, b): endpoints excluded (< >) |
|---|---|
| Closed interval | [a, b]: endpoints included (≤ ≥) |
| Compound (and) | a < x < b |
| Number line | open circle = strict, closed = inclusive |
Digital SAT reference
Area & Circumference
| Circle area | A = πr² |
|---|---|
| Circle circumference | C = 2πr |
| Rectangle | A = ℓw |
| Triangle | A = ½ b h |
Volume
| Rectangular box | V = ℓwh |
|---|---|
| Cylinder | V = πr²h |
| Sphere | V = 4⁄3 πr³ |
| Cone | V = 1⁄3 πr²h |
| Pyramid | V = 1⁄3 ℓwh |
Right triangles
| Pythagorean theorem | a² + b² = c² |
|---|---|
| 30°–60°–90° | sides x : x√3 : 2x |
| 45°–45°–90° | sides s : s : s√2 |
Constants
| Degrees in a circle | 360° |
|---|---|
| Radians in a circle | 2π |
| Angles of a triangle | sum = 180° |
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