#### Mathematics 3 ESO – Unit 7 SYSTEMS OF LINEAR EQUATIONS Page 61 – Activity 33

Watch the video on “Solving Simultaneous Equations by Graph” and answer:**a)**- I)What means that simultaneous equations can be solved graphically?
- II)Why are the equations in the example “linear equations”?

III)** **Why the points that we find to draw the lines are always on the axis?

- IV)After drawing the two lines, how do we find the solution to the system?
- V)Using a graphical method, can we always rely on being totally accurate? Why do you think that is?

Watch the video on “Solving Simultaneous Equations by Elimination” and answer:**b)**- I)Why do we want to find values of “x”?
- II)When we have the same number of “y’s”, why do we subtract the equations (not add them)?

III)** **When we have found the value of “x”, in what equation do we have to substitute the value of “x”?

- IV)How do we check that the solutions are correct?

Watch the video on “Solving Simultaneous Equations by Substitution” and answer:**c)**- I)When we use substitution, how do we combine both equations?
- II)Solve this system by substitution: x = 4y – 10 ; 2x + 5y = 6 and check the solutions.

Scroll down to the interactive window and play with theblue lines by moving the points on the lines. The red point is the solution.**d)**- I)What is the solution if the points on one line are (-2,3) and (2,3) and the points on the other line are (3,1) and (3,-2)?
- II)What is the solution if the points on one line are (-2,3) and (2,3) and the points on the other line are (1,0) and (3,-2)?