Let’s take a moment to overview integers:
➢ Just Imagine you are playing a game where you can win or lose
points.
➢ If you win, you get +5 or +10 points. But if you lose a game, you
lose your points likes -5 or -10.
➢ These numbers, both positive and negative are called Integers.
➢ They help us to keep track of gains and losses in real life, just like
in the game!
➢ It is a key idea in mathematics, integers are the collection of entire
numbers that can be zero, positive, or negative.
➢ They are represented by the letter Z, which is derived from the
German word “Zahlen,” which means “number”.
Example for Integer: lets consider a set of integers which is represented as Z
Z= {…,-3,-3,-1,0,1,2,3,…}
Zero: Zero (0) is neutral; it is neither positive nor negative.
Positive Integers: Z= {1, 2, 3, …}
Negative Integers: Z= {-1, -2, -3 ,…}
1)Closure under Addition:
- For any two integers a and b, a + b is an integers.
Let us see whether this property is true for integers or not.
Statement Observation
(i) 17 + 23 = 40 ___
(ii) (-10) + 3 = -7 ___
(iii) (-20) + 0 = _ ____
(iv) 3 + (-5) = -2 ___
2)Closure under Subtraction:
- For any two integers a and b, a – b is an integers.
What happens when we subtract an integer from another integer? Can we
say that their difference is also an integer?
Statement Observation
(i) 7 – 9 = -2 ____
(ii) (-10) – (-3) = 7 ____
(iii) 17 – (-21) = _ _____
(iv) 3 – (-5) = -2 _____
3)Commutative Property:
- For ant two integers a and b, we can say a + b = b + a
We know that 3 + 5 = 5 + 3 = 8, addition is commutative for whole numbers.
We have 5 + (-6) = -1 and (-6) + 5 = -1
So, 5 + (-6) = (-6) + 5
Are the following equal?
(i) (-8) + (-9) and (-9) + (-8)
(ii) (-45) + 0 and 0 + (-45)
And also we know that subtraction is not commutative for whole numbers.
Consider an integers 5 and (-3).
Is 5 – (-3) the same as (-3) – 5? No, Because 5 – (-3) = 8 and (-3) – 5 = -8.
4)Associative Property:
- In general, for ant two integers a and b, we can say a + (b + c) = (a + b) +c
Consider the integers 3, 2 and 5.
Look at 3 + (2 + 5) and (3 + 2) + 5 are equal?
Answer:
Yes, In both cases we get 10.
3 + (2 + 5) = 10 and (3 + 2) + 5 = 10.
Similarly consider -3, 1 and -7.
(-3) + [1 +(-7)] = -3 + _ =
[(-3) + 1] + (-7) = -2 + =_
Is (-3) + [1 +(-7)] same as [(-3) + 1] + (-7) ?
5)Additive Identity:
- 0 is the additive identity, (a + 0 = a).
Observe the following and fill in the blanks:
(i) (-8) + 0 = -8
(ii) (-23) + 0 = _ (iii) 0 + (-59) = _
(iv) -61 + _ = -61 (v) 0 + _ = -37
(vi) _ + 0 = _