Toán Tiếng anh: Đơn thức đồng dạng

Week 25 
Period 54 §4. SIMILAR MONOMIALS 
I/ Objectives: 
- The knowledge: Students will know how similar monomials are form and know 
how adding and subtracting for us 
- The skills: Students have ability to identify quickly similar monomials, perform 
operations on similar monomials exactly. Students have skills presenting Math 
solutions in English well 
- The attitude: Students have self-discipline in learning and group activities. There 
is a dynamic, creative life 
II/ Vocabulary: 
- Similar monomials: đơn thức đồng dạng 
- Distributive: Phân phối 
- Law: Qui tắc 
- Coefficients: Hệ số 
III/ Teaching and students aids: Book, notebook, ruler 
IV/ Content: 
 1/ Class organization: 
- Greeting 
- Checking attendance: How many students arre absent on today ? 
2/ Check up: 
a/ Find the value of the following expression 5x
2
y
2
 at x = -1 and y = -1/2 
b/ Find the degree of monomials then find the product of the following pairs of 
monomials below: -1/2x
2
y
3
 and 5x
2
y
2
3/ New lesson: 
Teachers activities Students activities Content 
Divide into two groups ( 
group A: degree 2,3; group 
B: degree 5,6,7 ) and 
complete the following 
exercise. 
Student do all within 5 
minutes 
What are the similar 
monomials ? 
Ask a student present before 
class. Who’s correct ? 
Slove the following 
problem 
Ask a student to on the 
board 
Read the statement above 
Son said right 
1/ Similar monomilars: 
? 1 Give monomial 3x
2
yz 
a/ Write three the 
monomials that have the 
same algebraic factor to the 
monomials above 
b/ Write the monomias that 
have the different algebraic 
factor to the monomial 
above 
Thus: The two similar 
monomials are pairs of 
monomials have the 
coefficients not equal but 
the same algebraic factor 
Example: 2x
3
y
2
, -5x
3
y
2
 and 
1/4x
3
y
2
 are similars 
monomials 
Note: The numbers equal 0 
are similar monomials 
? 2 Who’s correct ? 
Give remark to the student’s 
Ask a student to represent 
in front of class: 
Is there following 
monomials similar above or 
not ? 
a. x2 and x3 
b. 2xyzx2 and 5x2yzx 
c. x2y and yx2 
Do you use law ? 
Ask a student to write on 
the board 
Give remark to the students 
answers: Is your solution 
right or wrong ? 
Slove following problem 
a. Similar 
b. Not similar 
c. Simplify then Similar 
Use distributive law 
Repeat the statement above 
Do ? 3 
Son said: 0,9xy
2
 and - 
0,9x
2
y are similar 
monomial 
Phuc said: The two 
monomials above not 
similar. How about your 
ideas ? 
Note: Any number not 
equal to 0 is a monomials 
2/ Adding and subtracting 
the similar monomials 
Example 1: Let us add 2x
2
y 
and x
2
y 
Solution: 
2x
2
y + x
2
y = (2+1)x
2
y = 3 
x
2
y 
Example 2: Let us subtract 
7xy
2
 and 3xy
2
Solution: 
3xy
2 
- 7xy
2 
= ( 3 -7 ) xy
2 
 = -
4 xy
2 
Law: The sum ( difference ) 
of two or more like term is 
a like term with a numerical 
coefficient equal to the sum 
( difference ) of the 
numerical coefficients of all 
the like terms 
? 3 Let us add xy
3
; 5xy
3 
and 
-7xy
3
Solution: 
xy
3
 + 5xy
3
 – (-7xy3 ) = - xy3 
 4/ Consolidation: 
Exercise: Who can do it ? 
16/34: Let us add: 25xy
2
; 55xy
2
 and 75xy
2
17/35: Find the value of the following expression when x = 1 and y = -1 
1/2x
5
y – 3/4x5y + x5y ( Is there any other way to solve the problem ? ) 
5/ Homework: 
- Review all the lesson, we learn today 
- Solve the following exercise 19, 20/ paper 34, 35 
Hit: Use the value of the following expression previous lesson