Second Term Lesson Note for Week Four.
Class : JSS 3 (Basic 9)
Subject : Mathematics
Topic : Solving Simultaneous Equation using Graphical Method
Duration : 80 Minutes
Period : Double Period
Reference Book :
- Essential Mathematics for Junior Secondary School, JSS 3 (Basic 9)
- Lagos State Unified schemes of work for Junior Secondary School, JSS 1 – 3.
- Online Resources
Instructional Material : Chart showing the graphical methods of Simultaneous Equation.
Learning Objectives : By the end of the lesson learners will be able to :
i. Describe simultaneous Equation
ii. Identify the various methods used in solving Simultaneous Equation.
iii. Explains the use of graph to solve simultaneous Equation.
Content :
SOLVING SIMULTANEOUS EQUATION GRAPHICALLY
To solve simultaneous equations graphically.
1. Make a table of values for both equations.
2. Draw the graphs for both equations on the same axes
3. Find the co-ordinate (i.e x and y values) where both graphs intersect these values are the solutions of both equations.
4. Check your solutions by putting these values into the original equations to make sure they satisfy them.
Example 16.3 :
Solve the simultaneous equations.
X – 2y = 4 and 2x – y = 5 graphically
Solution :
In each equation make y the subject of the equation. From equation (1), we have :
(i) x – 2y = 4
-2y = 4 – x
y = -2 + 0.5x ……………… (1)
Then substitute values or range for x, that is x = 0, 1, 2, and 3 respectively. Hence record the corresponding values for y.
Make a table for the equation (1) above as shown below :
| x | 0 | 1 | 2 | 3 |
| y | – 2 | – 1.5 | – 1 | – 0.5 |
From equation (2), make y the subject of the formula :
2x – y = 5 ……………… Eqn. (2)
– y = 5 – 2x (multiply through by minus)
– ( – y) = – 5 – (- 2x)
y = 2x – 5
| x | 0 | 1 | 2 | 3 |
| y | – 5 | – 3 | – 1 | 1 |
Plot the graph of the two Equations for table 1 and table 2.
The point of intersection where the two lines cut each other is the values and answer to the given simultaneous Equations.
Evaluation :
Solve the simultaneous Equation given below using graphical method
1. y + 2x = 5 and 3x – 2y = 4
2. 3x + 2y = 8 ……………. (1)
x + 2y = 4 ……………… (2)