SAT Math · Study & Practice
Rational Expressions
A rational expression is a fraction with polynomials on top and bottom. The SAT tests simplifying, the four operations and solving rational equations. This chapter covers simplification, multiplication, division, addition, subtraction and rational equations. Read each topic, try the problems with the hint ladder, then take the 8-question topic test.
Topics
1
Simplification
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2
Multiplication
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3
Division
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4
Addition
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5
Subtraction
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6
Rational Equations
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Chapter test
Formula Reference Sheet
This chapter
Operations
| Simplify | factor top and bottom, cancel common factors |
|---|---|
| Multiply | (a/b)(c/d) = ac/bd |
| Divide | (a/b) ÷ (c/d) = (a/b)(d/c) |
| Add/subtract | use a common denominator |
Cautions
| Restrictions | denominator ≠ 0 (exclude those x) |
|---|---|
| Solve equations | clear denominators, then solve |
| Check | reject answers that make a denominator 0 |
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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