Module 1 Pre-Lesson 30: Linear Systems in Two Variables
Warm Up: There are three methods for solving a system of equations in 2
variables: substitution, elimination, graphing. Do each one for the following
system:
Example 1:
2x + 3y = 7 2x + y = 3
Substitution: Elimination: Graphing
Procedures:
Substitution:
Solve one equation for a variable.
Substitute the equation into the other.
Solve for first variable.
Plug into other equation and solve for second variable.
Elimination:
If necessary, multiply one or both equations so that coefficient matches.
Add or subtract equations.
Solve for first variable.
Plug into other equation and solve for second variable.
Example 2:
5𝑥 −2𝑦 = 4 −2𝑥 + 𝑦 = 2
Example 3:
-16x + 7y = -18 8x – 8y = 0
Example 4:
5x – 14y = -2 -2x +7y = -2
Example 5:
-x – 5y = -26 -5x + y = 0
Exit Ticket:
Solve using substitution, elimination, and graphing:
3x – 6y = 30 5x – 2y =18