Grade 10 → Number Systems → Real Numbers ↓
Properties of Real Numbers
Real numbers form a broad category in the number system, which includes natural numbers, whole numbers, integers, rational numbers, and irrational numbers. Understanding the properties of real numbers helps to simplify expressions and solve equations efficiently. In this lesson, we will explore various properties of real numbers with lots of examples and explanations.
1. Exchangeable assets
The commutative property states that changing the order of numbers in an addition or multiplication operation does not change the result.
1.1 Commutative property of addition
a + b = b + a
Example:
- If
a = 5
andb = 3
, then5 + 3 = 3 + 5
which both equal8
.
1.2 Commutative property of multiplication
a * b = b * a
Example:
- If
a = 4
andb = 6
, then4 * 6 = 6 * 4
which both equal24
.
2. Associative property
The associative property shows that the way numbers are grouped in an addition or multiplication operation has no effect on their sum or product.
2.1 Associative property of addition
(a + b) + c = a + (b + c)
Example:
- If
a = 2
,b = 4
, andc = 6
, then(2 + 4) + 6 = 2 + (4 + 6)
both give the result12
.
2.2 Associative property of multiplication
(a * b) * c = a * (b * c)
Example:
- If
a = 3
,b = 5
, andc = 2
, then(3 * 5) * 2 = 3 * (5 * 2)
which both calculate to30
.
3. Distributive property
The distributive property connects addition and multiplication. It states that the number multiplied by the sum of two numbers is equal to the sum of the products of that number and each number.
a * (b + c) = a * b + a * c
Example:
- If
a = 2
,b = 3
, andc = 4
, then2 * (3 + 4) = 2 * 3 + 2 * 4
both will give result14
.
4. Identity property
The identity property of addition states that when you add zero to any real number, it remains unchanged. Similarly, the identity property of multiplication states that any real number remains unchanged when you multiply it by one.
4.1 Identity property of addition
a + 0 = a
Example:
- If
a = 7
, then7 + 0 = 7
.
4.2 Identity property of multiplication
a * 1 = a
Example:
- If
a = 5
, then5 * 1 = 5
.
5. Inverse property
The inverse property states that adding any number to its additive inverse (opposite) gives zero, and multiplying any number by its multiplicative inverse (inverse) gives one.
5.1 Additive inverse
a + (-a) = 0
Example:
- If
a = 9
, then9 + (-9) = 0
.
5.2 Multiplicative inverses
a * (1/a) = 1
(assume that a ≠ 0
)
Example:
- If
a = 8
, then8 * (1/8) = 1
.
6. Closing assets
The closure property shows that performing an operation on any two numbers in a set always yields a number within the same set. Real numbers are closed under addition, multiplication, and subtraction but not under division.
6.1 Closure property of addition
If a
and b
are real numbers, then a + b
is also a real number.
a ∈ R, b ∈ R ⇒ a + b ∈ R
6.2 Closure property of multiplication
If a
and b
are real numbers, then a * b
is also a real number.
a ∈ R, b ∈ R ⇒ a * b ∈ R
7. Additional examples and ideas
Understanding these properties is important for solving algebraic expressions efficiently. Consider another example for the associative property:
Example of associative property
Let us take a = 1
, b = 2
, and c = 3
.
Using the associative property of addition:
(1 + 2) + 3 = 3 + 3 = 6
1 + (2 + 3) = 1 + 5 = 6
Example of exchangeable assets
For the commutative property of multiplication:
- If
a = 10
andb = 4
, then10 * 4
and4 * 10
both equal40
.
Understanding these properties helps to simplify complex equations before performing lengthy calculations. Our goal is to set up formulas and simplify polynomial expressions using these properties.
Conclusion
The properties of real numbers are a foundational aspect of mathematics, helping us to understand and manipulate numbers effectively. From basic operations to solving complex equations, these properties are invaluable tools that simplify calculations and enable a deeper understanding of mathematical concepts. Memorize the key properties: commutative, associative, distributive, identity, inverse, and closure. Mastering these properties can help students confidently tackle various mathematical problems and equations they encounter during their academic journey.