Mathematics 4 ESO – Unit 5 SYSTEMS OF EQUATIONS extra activities
1 – Watch the video on ” Solving Systems by Substitution”.
 a) Why can we replace the “y” in the second equation for “(3x + 2)”?
 b) After finding the value of “x”, how do we find the value of “y”?
 c) Solve the system by substitution: y = 5x – 6 ; 6x + 2y = 4
 d) Solve the system by substitution: 3x + 2y = 10 ; x = 3y + 6
2 – Watch the video on “Solving Systems of Equations”. The video explains how to solve a system of equations by addition (also called “elimination”).

 a) To solve the system of equations, what is our first goal?
 b) What do we do after cancelling out the “y” variable?
 c) Solve the system by addition: 5x – y = 1 ; 6x + y = 10
 d) Solve the system by addition: x + 2y = 0 ; x – 3y = 1
3 – Watch the video on “Solve a System of Equations Using Eliminations”.

 a) What are the different ways to solve systems of equations?
 b) Why do we multiply both sides of the second equation by 3?
 c) After finding the value of “x”, what do we do?
 d) When we represent the system of equations graphically, what is the solution to the equation?
 e) Solve the system by elimination (also called “addition”: 3x – y = 3 ; x + y = 5 and verify the solution graphically.
“Solving systems of linear equations — Basic example”:
4 – Click on the link and watch the video on “Solving systems of linear equations — Basic example”.
 a) In what case a system of linear equations has one solutions?
 b) In what case a system of linear equations has no solution?
 c) In what case a system of linear equations has infinite solutions?
 d) In what case a system of linear equations has two solutions?
 e) Why in this example we can’t have two solutions?
 f) How do we know that the lines are going to have one solution?