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Revision Notes
Rational Numbers — Revision Notes
Gujarat Board · Class 8 · Mathematics
Rational Numbers revision notes for Gujarat Board Class 8 Mathematics: 4 topics in quick points. Part of the Gujarat Board Class 8 Mathematics syllabus.
45 questions4 formulas & key relations5 concepts
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Key Topics to Revise
1
What Are Rational Numbers?
- A rational number is any number that can be written as p/q where p and q are integers and q ≠ 0.
- Examples: -2/3, 6/7, 9/-5, 0, -2, 4 are all rational numbers.
- Every integer is a rational number (e.g., -2 = -2/1).
2
Closure Property
- A set is CLOSED under an operation if performing that operation on any two numbers from the set always gives a result that is also in the set.
- Rational numbers are CLOSED under addition: a + b is always a rational number.
- Rational numbers are CLOSED under subtraction: a - b is always a rational number.
3
Commutativity Property
- An operation is COMMUTATIVE if changing the order of the two numbers does NOT change the result.
- Addition is commutative for rational numbers: a + b = b + a.
- Multiplication is commutative for rational numbers: a × b = b × a.
4
Associativity Property
- An operation is ASSOCIATIVE if grouping of numbers does NOT change the result: a * (b * c) = (a * b) * c.
- Addition is associative for rational numbers: a + (b + c) = (a + b) + c.
- Multiplication is associative for rational numbers: a × (b × c) = (a × b) × c.
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Full NotesKey Concepts
A rational number is any numberA set of numbers is closedAn operation is commutative if changingAn operation is associative ifZero is the additive identity
Frequently Asked Questions
What are the important topics in Rational Numbers for Gujarat Board Class 8 Mathematics?
Key topics in Rational Numbers include What Are Rational Numbers?, Closure Property, Commutativity Property, Associativity Property. Study these first, then practise questions on each for Class 8 exams.
How should I revise Rational Numbers for Class 8 exams?
Learn the core ideas first, then work through the 45 practice questions on Rational Numbers. Revise definitions regularly and use flashcards for quick recall before the exam.
Sources & Official References
Content is aligned to the official syllabus. Refer to the board website for the latest curriculum.
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