MULTIPLICATION OF INTEGERS Pre requisite knowledge 1.concept of integers 2.concept of representation...
-
Upload
cadence-orourke -
Category
Documents
-
view
230 -
download
2
Transcript of MULTIPLICATION OF INTEGERS Pre requisite knowledge 1.concept of integers 2.concept of representation...
Pre requisite knowledge 1.concept of integers
2.concept of representation of integers on number line.
3.concept of addition and subtraction of integers.
4.concept of multiplication of two whole numbers.
Teaching points 1.while multiplying a positive integer and a negative integer,we multiply them as whole
numbers and put a minus sign before the product . We thus get a negative integer
2. The product of two negative integers is a positive integer.we multiply the two negative
integers as whole numbers and put the positive sign before the product.
Continued 3. If the number of negative integers in a
product is even, then the product is a positive integer. If the number of negative integers in a product is odd, then the product is a negative
integer.
Product of two in tegers
by activity method.
Instructional objectives To enable students to know that multiplication of
integers is repeated addition
2.to enable students to know that multiplication of two positive integers through patterns.
3.to enable students to multiply two negative integers.
4.to enable students to find the product of theree or more negative integers
5.to enable students to find the product of two integers by activity method.
Multiplication of positive and negative integers
Multiplication of wholenumbers is repeated addition
5+5+5=3x5=15
Addition of integers can be represented in the same way
(-5)+(-5)+(-5)=-15=3x(-5)
0-5-10-15-20
Find (-3)x5 through the following pattern
3x5=15
2x5=10=(15-5)
1x5=5=(10-5)
0x5=5-5=0
-1x5=0-5=-5
-2x5=-5-5=-10
-3x5=-10-5=-15
We already have 3x(-5)=-15
So we get (-3)x5=-15=3x(-5)
While multiplying a positive integer and a negative integer,we multiply them as wholenumbers and put a minus sign before the product.we thus get a negative
integer
Continued We already have 3x(-5)= -15
So we get (-3)x5 = -15 = 3x(-5)
While multiplying a positive integer and a negative integer,we multiply them as whole
numbers and put a minus sign before the product. We thus get a negative integer .
Multiplication of two negative integers.
Observe the pattern for (-3)x(-2)
(-3)x4=-12
(-3)x3=-12-(-3)= -12+3= -9
(-3)x2=(-9)-(-3)-9+3= -6
(-3)x1=(-6)-(-3)=-3
(-3)x0= -3-(-3)=0
(-3)x -1=0-(-3)=3
(-3)x(-2)=3-(-3)=6
Continuedfrom the pattern , we observe
(-3)x(-1)=3=3x1(-3)x(-2)=6= 3x2
the product of two negative integers is a positive integer.We multiply the two negative integers as whole numbers and put the positive
sign before the product
Product of three or more negative integers
(-4)x(-3)=12
(-4)x(-3)x(-2)=[(-4)x(-3)]x(-2)=12x(-2)=
-24
(-4)x(-3)x(-2)x(-1)=[(-4)x(-3)x(-2)]x(-1)
=(-24)x(-1)
Continued If the number of negative integers in a
product is even , then the product is a positive integer . If the number of negative integers in
a product is odd, then the product is a negative integer.
Two find the product of two integers by activity method
0-1-2-3-4-5 1 2 3 4 5
00-1-1-2-2-3-3-4-4 -5-5 11 22 33 44 55
Activity continued
00
00
-1-1
--11
--11--11
-1-1
-1-1
-2-2
-2-2
-3-3
-3-3
1122
33
11 22 33
-4-4
--44-4-4 44
44
P(2)P(2)
Activity continued
00
00
-1-1--22
-2-2-3-3-4-41111
2233 44
-1-1-- -2-2-3-311 33 4455 66
P(-2)P(-2)
11 22 334466