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Chapter 2 of 9
Flashcards

Real Numbers

Tamil Nadu Board · Class 9 · Mathematics

Flashcards for Real Numbers — Tamil Nadu Board Class 9 Mathematics. Quick Q&A cards covering key concepts, definitions, and formulas.

45 questions25 flashcards5 concepts

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A nested Venn diagram illustrating the relationships between natural numbers (N), integers (Z), rational numbers (Q), and real numbers (R) as subsets of each other.
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25 Flashcards
Card 1Denseness Property of Rational Numbers

Find any two rational numbers between 1/2 and 2/3.

Answer

Step 1: Use the formula (p+r)/(q+s) where p/q = 1/2 and r/s = 2/3. Step 2: First rational number = (1+2)/(2+3) = 3/5 Step 3: Find another between 1/2 and 3/5 = (1+3)/(2+5) = 4/7 Verification: 1/2 = 0.

Card 2Conversion of Terminating Decimals to Rational Numbers

Convert the decimal 2.945 into the form p/q where p and q are integers and q ≠ 0.

Answer

Step 1: Write 2.945 = 2 + 0.945 Step 2: 0.945 = 945/1000 (move decimal 3 places) Step 3: Convert to mixed number: 2.945 = 2 + 945/1000 = (2 × 1000 + 945)/1000 = 2945/1000 Step 4: Simplify by finding G

Card 3Conversion of Non-terminating Recurring Decimals

Convert 0.35̄ (where 5 repeats) into p/q form.

Answer

Step 1: Let x = 0.3555... Step 2: Multiply by 10: 10x = 3.555... Step 3: Multiply by 100: 100x = 35.555... Step 4: Subtract equation 2 from equation 3: 100x - 10x = 35.555... - 3.555... Step 5: 90x =

Card 4Classification of Real Numbers

Classify these numbers as rational or irrational: (i) √10 (ii) √49 (iii) 0.025 (iv) 0.76̄

Answer

Step 1: √10 - Check if 10 is a perfect square. It's not (3² = 9, 4² = 16). √10 is IRRATIONAL Step 2: √49 - This equals 7 = 7/1, which is RATIONAL (49 is a perfect square) Step 3: 0.025 - This is a ter

Card 5Simplification of Surds

Express √8 in simplest form (as a pure surd).

Answer

Step 1: Factor 8 = 4 × 2 = 2² × 2 Step 2: √8 = √(4 × 2) Step 3: √8 = √4 × √2 (using law of radicals) Step 4: √8 = 2√2 Answer: 2√2 Verification: (2√2)² = 4 × 2 = 8 ✓ Note: Pure surd has coefficient 1,

Card 6Simplification of Cubic Surds

Express ∛192 in simplest form.

Answer

Step 1: Factor 192 = 64 × 3 = 4³ × 3 Step 2: ∛192 = ∛(64 × 3) Step 3: ∛192 = ∛64 × ∛3 (using law of radicals) Step 4: ∛192 = 4∛3 Verification: (4∛3)³ = 4³ × 3 = 64 × 3 = 192 ✓ Answer: 4∛3 Order of sur

Card 7Addition and Subtraction of Surds

Add: 3√7 + 5√7. Is the answer rational or irrational?

Answer

Step 1: Identify like surds - both have √7 (same radicand) Step 2: Apply addition rule: a√b + c√b = (a + c)√b Step 3: 3√7 + 5√7 = (3 + 5)√7 Step 4: = 8√7 Answer: 8√7 (IRRATIONAL) Explanation: When we

Card 8Addition and Subtraction of Surds

Simplify: √63 - √175 + √28

Answer

Step 1: Simplify each surd separately √63 = √(9 × 7) = 3√7 √175 = √(25 × 7) = 5√7 √28 = √(4 × 7) = 2√7 Step 2: All have same radicand (7), so they are like surds Step 3: Combine: 3√7 - 5√7 +

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Frequently Asked Questions

What are the important topics in Real Numbers for Tamil Nadu Board Class 9 Mathematics?
Key topics in Real Numbers include Real Numbers Classification and Properties, Real Numbers – Complete Classification Mind Map, Real Numbers: Complete Hierarchy and Classification. These are the concepts Tamil Nadu Board Class 9 examiners draw on most — study them first, then practise related questions.
How to score full marks in Real Numbers — Tamil Nadu Board Class 9 Mathematics?
Understand the core concepts first, then work through the 45 practice questions available for this chapter. Revise formulas and definitions regularly, and use flashcards for quick recall before the exam.
How many flashcards are available for Real Numbers?
There are 25 flashcards for Real Numbers covering key definitions, formulas, and concepts. Use them daily for 10–15 minutes for best results.

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Content is aligned to the official syllabus. Refer to the board website for the latest curriculum.

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