This lesson plan aims to teach students how to determine the zeros of quadratic functions using completing the square. The objectives are for students to be able to identify the steps of completing the square, use it to find zeros of quadratic functions, and understand how to apply the method. An example problem walks through solving an equation using completing the square. Students will then practice solving quadratic equations this way. The lesson evaluates students by having them use completing the square to solve practice problems and uncover the answer to a riddle about vitamins.

1. LESSON PLAN IN
MATHEMATICS IV
(Zeros of Quadratic Functions by Completing the Square)
September 3, 2010
Competency: determine the zeros of quadratic functions using completing the square
I.
OBJECTIVES:
At the end of the lesson, the students should be able to:
1. Identify the different steps in performing completing the square;
2. Determine the zeros of quadratic functions using completing the
square; and
3. Manifest understanding on determining the zeros of quadratic
functions using completing the square.
II.
SUBJECT MATTER:
1. Topic:
QUADRATIC FUNCTIONS
2. Sub-topic:
Zeros of Quadratic Functions by Completing the Square
3. References:
(1) Advanced Algebra, Trigonometry and Statistics,
Dilao, et.al pages 68-70
(2) Worktext in Advanced Algebra, Trigonometry and Statistics
Pascual, et. al. pages 137-138
4. Materials:
5. Strategies:
III.
visual aids
exposition and discussion
PROCEDURES:
A. Preliminary Activities:
1. Opening Prayer
2. Checking of attendance, cleanliness and orderliness of the room.
B. Checking of assignment
C. Presentation of the Lesson
The roots of a quadratic function are easily obtained by factoring. When
the left member of a quadratic function is not factorable, another method called
completing the square is applied.

2. Illustrative Example:
Solve f(x) = x2 + 6x + 7 using completing the square.
Solution:
1. Write the function f(x) = x2 + 6x + 7 in the form
x2 + 6x + 7 = 0
2. Transposed +7 on the other of the equation.
x2 + 6x = -7
3. Complete the square by getting the half of the numerical coefficient of the
second term then square it. Add it to both side of the equation.
x2 + 6x + (3)2 = -7 + (3)2
4. Write the left member as a perfect square trinomial. Solve the equation.
(x + 3)2 = - 7 + 9
(x + 3)2 = 2
=
x+3=±
x+3=
x+3=-
x = -3 +
x=-3-
D. Activity:
Solve the following quadratic equation by completing the square.
1. 3x2 + 5x – 2 = 0
2. 2x = 5 +
E. Generalization:
What are the different steps in solving quadratic functions by completing the
square?
IV.
EVALUATION:
RIDDLE:
What are the six main vitamins?
Solve the quadratic functions by completing the square. Write the letter of
the correct answer in the box provided to find out the answer on the riddle.

3. 1. x2 – 6x – 4 = 0
2. 2x2 – 5x – 4 = 0
3. x2 + bx = c
4. x2 – 2x – 3 = 0
5. 2x2 = x + 3
6. 4x2 – 4x – 7 = 0
B
F
-
E
D
and 2
G
A
I
V.
2
3
C
H
L
-1 and -3
K
-1 and 3
4
J
and 2
5
6
&
ASSIGNMENT:
Solve the following using completing the square.
1.
= 3x + 2
2.
=
Demonstrated by:
ERWIN J. CABIGAO
Mathematics Teacher
Observed by:
MA. CORAZON P. LOJA
EPS-1, Mathematics
1