Systems of Linear Equations
Section: AlgebraGRE frequency: Very HighPro
1. Core Idea
Two equations, two unknowns. Three methods:
- Substitution — best when one variable is already isolated (or easy to isolate).
- Elimination — best when coefficients line up or can be matched quickly.
- Combination shortcut — the GRE favourite: when the question asks for
x + yorx - y, you often get it by adding or subtracting the equations directly, without solving for either variable.
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