Lesson 27 Linear Equations Choosing the Best Method

Warm-Up Solve one of the systems below using any method. Explain why you chose your method. a. y = 5 x – 4 x + 2 y = 25 b. 2 x + 7 y = 1 – 2 x + 2 y = – 10 c. y= x– 4 y = – 3 x + 3

Choosing the Best Method Target: Choose the best method for solving a given system of equations.

Choosing a Method to Solve a System of Linear Equations � Graphing: Both equation are in slope-intercept form. � Tables: Both equations are in slope-intercept form and the slope is an integer. � Substitution: A variable is isolated in one equation. � Elimination: Both equations are in standard form and the variables are lined up in columns.

Example 1 a Choose the best method to solve the system of equations. Explain your reasoning. x – 2 y = 10 3 x + 2 y = 6 � Elimination � The y-variable will easily be eliminated.

Example 1 b Choose the best method to solve the system of equations. Explain your reasoning. y = 2 x – 3 4 x – 5 y = – 1 � Substitution � The first equation is already solved for y.

Example 1 c Choose the best method to solve the system of equations. Explain your reasoning. y= x y = 2 x + 7 � Graphing � The equations are already in slope-intercept form.

Example 1 d Choose the best method to solve the system of equations. Explain your reasoning. y = 5 x – 9 y = 2 x – 3 � Tables � The equations are already in slope-intercept form and the slopes are integers.

Exit Problems Write a sample of a system of equations that would be best solved by… a. elimination b. graphing c. substitution

Communication Prompt Choose one method for solving a system of equations. Describe how the equations might be set up that would allow you to solve with your method easily.