Math
Substitution method.
Definition
A technique for solving systems of equations by solving one equation for one variable and substituting that expression into the other equation. This reduces the system to a single equation with one variable.
How it works · 4 phases
Step by step.
- Solve one equation for one variable in terms of the other.
- Substitute that expression into the other equation.
- Solve the resulting single-variable equation.
- Substitute back to find the value of the other variable.
Examples
Real-world.
- 1 Given y = 2x and x + y = 9: substitute to get x + 2x = 9, so x = 3, y = 6
- 2 Given 3x + y = 7 and x − y = 1: solve second for x: x = y + 1, then 3(y+1) + y = 7 → y = 1, x = 2