Republic of the Philippines
SOUTHERN LUZON STATE UNIVERSITY
JUDGE GUILLERMO ELEAZAR
Tagkawayan, Quezon
DETAILED LESSON PLAN
IN MATHEMATICS 8
I. OBJECTIVES:
At the end of the lesson, the learners are expected to:
1. Illustrate linear equations in two variables and determine the solutions to systems of linear
equations in two variables
2. Solve System of Linear Equation in two variables by elimination method; and
3. Apply the substitution principle to check whether the answer/s is/are correct
II. SUBJECT MATTER
A. Topic: Solving systems of Linear Equations in two Variables by Elimination Method
B. Materials: Visual Aids, Chalk, Board and PowerPoint Presentation.
C. Values: Develop the critical thinking skills
III. PROCEDURE
TEACHER’S ACTIVITY
STUDENT’S ACTIVITY
A. PREMLIMINARIES
1. PRAYER
“Please stand up”
(All students will stand up)
“Roselyn, please lead a prayer”
(Student will lead the prayer)
GREETINGS
“Good morning class”
Good morning, ma’am Christine
CLASSROOM MANAGEMENT
“Please arrange your chairs and pick up the
pieces of papers under your chairs”
(Student will arrange their chairs and pick up the
pieces of paper)
“Okay please sit down and be silent”
(Checking of Attendance)
“If I call your name, please say present”
“We have here,” student name.
“Alright I’m glad to see that you are all present
for today’s”
Yes ma’am
(Present ma’am)
I know you are really excited for our lesson today
before that lets review our last topic
2. REVIEW:
What is our topic last meeting
Solving systems of Linear Equations in two
Variables by Elimination Method
What are the step by step in Solving systems of
Linear Equations in two Variables by
Elimination Method
3. MOTIVATION
None ma’am!
Before we start our day, let’s first play a game.
Who familiar with the game Wordsearch?
Amazing! It seems that most of you are familiar
with the game.
(Students will answer the game.)
I will group you into 5
You need to find the word
Expected Answers:
1. Solving System.
2. Variables
3. Method
4. Elimination
5. Additive Inverse
6. Linear Equation
7. Addition
B. PRESENTATION/ DISCUSSION
To begin our discussion So, let’s first
define what is linear equation in two
variables?
Very Good!
(Student will define Linear Equation in two
variables)
A linear equation in two variables is an
equation that can be written in the form
Ax + By=c, where a, b, and c are real
numbers, a ≠ 0 and b ≠ 0.
For example:
5x + 3y = 4 0r x + y = 20
Let’s try to answer these examples based
on the definition of Linear Equation:
Tell whether if the following is a linear
equation in two variables or not.
1. X + y = 4
2. 2x = 4y – 2
3. 5x – 3 = 12
4. 12 = 2x + 3y
5. X
2 – 3y = -5
6. 7 = 10 – x
(Possible answers of the students)
1. Linear Equation in Two Variables
2. Linear Equation in Two Variables
3. NOT
4. Linear Equation in Two Variables
5. NOT
6. Linear Equation in Two Variables
Very Good!
Now let’s define what is System of Linear
Equation?And what are the steps in
solving system of linear
equations by elimination method
Excellent!
A System of Linear Equation is a set of
two or more linear equations that have
variables in common.
Now let’s discuss the steps in solving
systems of linear
equations by elimination method.
(Student will define System of Linear Equation)
Steps:
1. Decide which variable you want to
eliminate.
2. Multiply one or both equations by the
appropriate constants so that the variable
that
you want to eliminate becomes additive
inverse
of each other.
3. Add the resulting equations.
4. Solve the equation obtained in STEP 3.
5. Substitute the value of the variable
obtained in
STEP 4 into one of the original equations
and
solve for the other variable.
6. Check your solution in both original
equations
Example:
Eq 1. X + y = 6
Eq 2. 2x + y = 8
(x + y = 6) -2
-2x – 2y = -12 eq. 1
2x + y = 8 eq. 2
0 -y = -4
-y = -4
(-y = -4) -1
y=4
now to get the value of x? what is the next step?
4. Solve the equation obtained in STEP 3.
5. Substitute the value of the variable
obtained in
STEP 4 into one of the original equations
and
solve for the other variable.
Who wants to solve
Eq. 1
x+y=6
y= 4
After that lets check our answer
Eq. 1 x + y = 6
X+4=6
X=6–4
X= 2
y= 4
Who wants to try?
Substitute the value of x and y
Eq 1. X + y = 6
Eq 2. 2x + y = 8
Eq 1. X + y = 6
2+4=6
6=6
We have the value of x = 2 and y = 4
Eq 2. 2x + y = 8
2(2) + 4 = 8
4+4=8
8=8
Activity
Solve Me!
Directions: Solve the following system of linear
Equation in two Variables using Elimination
method. Show your complete solution and
checking.
Solve each system by elimination.
1. 10x − 8y = 4 −5x + 3y = −9
2. −15x + 9y = 27 −5x − y = 17
3. −7x − 8y = −23 4x + 4y = 12
4. −3x − 10y = −4 x − 5y = 18
5) 10x + 10y = −10 −9x + 2y = −24
6) 4x − 8y = −4 −12x + 5y = −26
7) −5x − y = 2 4x + 3y = 5
8) x − 2y = −1 −5x + 8y = 11
D. Generalization
What is Linear Equation in two variables
A linear equation in two variables is an equation
that can be written in the form Ax + By=c, where
a, b, and c are real numbers, a ≠ 0 and b ≠ 0.
What is system of linear equation in two variables
A System of Linear Equation is a set of two or
more
linear equations that have variables in common.
E. Evaluation
Directions: Identify the terms that can be
eliminated. If elimination by addition or
subtraction cannot be directly performed, state
first the number or numbers that should be
multiplied to one or both equations (see
example). Then solve each system by elimination.
Check your solutions.
F. Assignment
A. Research the steps how to solve the following:
1. Solving System of Linear Equations in Two
Variables
by Graphing
Prepared by:
Rombaon, Christine G.