8th Grade · Expressions & Equations
Elimination
8.EE.C.8b
Definition
A method for solving a system by adding or subtracting the equations to cancel one variable, leaving a single-variable equation to solve.
Examples
- 3x+y = 10 and 2x-y = 5: adding cancels y, giving 5x = 15, x = 3.
- If needed, multiply an equation first to create opposite coefficients.
Key rule
Line up the equations and add or subtract so one variable cancels.
Memory hook
Add or subtract to cancel a variable.