Number System Class 9 Maths One-Shot Full Chapter Revision | CBSE Class 9 Exams |BYJU'S Class 9 & 10

BYJU'S - Class 9 & 10・2 minutes read

The session covers the number system and preparation for polynomials, with examples of rational and irrational numbers and operations on real numbers explained in detail. Baiju's classes provide personalized attention, doubt clarification, and session notes through a Telegram channel for effective learning and understanding.

Insights

  • Real numbers are divided into rational numbers (expressed as fractions) and irrational numbers (cannot be expressed as fractions), with examples like pi and square roots falling into the latter category.
  • Plotting irrational numbers involves using right-angle triangles with a height of 1 and applying the spiral method, with the hypotenuse representing the square root of the desired number, emphasizing ease of construction and visualization on a number line.

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Recent questions

  • What are rational and irrational numbers?

    Rational numbers can be expressed as fractions, while irrational numbers cannot.

  • How are decimal expansions classified?

    Decimal expansions can be terminating, non-recurring recurring, or non-recurring.

  • How are rational and irrational numbers plotted on a number line?

    Rational numbers are plotted using fractions, while irrational numbers use square roots.

  • What is the process of rationalization?

    Rationalization involves multiplying and dividing by the conjugate of the denominator.

  • What are the laws of exponents?

    Laws of exponents include rules for multiplying and adding exponents.

Related videos

Summary

00:00

Grade 9 Math: Number System Overview

  • The session is about the number system, with participants like Dus, Saranya, Pesh, Archit, Rafiq, Jaguarti, Shan, Prashanth, Malaysia, Deb, Charan, Prieta, and others.
  • The session aims to cover the first chapter of grade 9 math, the number system, and prepare for the next chapter on polynomials.
  • Baiju's classes offer a two-teacher advantage for personalized attention and doubt clarification.
  • A Telegram channel provides session notes, updates, revision questions, and more.
  • Real numbers are categorized into rational numbers (expressed as fractions) and irrational numbers (cannot be expressed as fractions).
  • Rational numbers include integers, whole numbers, and natural numbers, while irrational numbers include examples like pi and square roots.
  • Equivalent rational numbers have common factors that simplify to the same value, like 1/2 and 2/4.
  • An example question involves finding the equivalent rational number of 16/28, which simplifies to 4/7.
  • Understanding irrational numbers between two positive numbers, like the square root of the product, helps identify irrational numbers within a range.
  • Decimal expansions can be terminating (like 0.75), non-terminating recurring (like 0.7858585), or non-recurring (like 3.1428976). Terminating and recurring decimals are rational, while non-recurring non-terminating decimals are irrational.

15:06

Types of Numbers and Plotting on Line

  • Decimal expansion types: terminating, non-terminating, non-terminating and recurring, non-terminating and non-recurring.
  • Rational vs. irrational numbers: rational numbers can be expressed as fractions, irrational numbers cannot.
  • Example of a non-terminating decimal expansion.
  • Plotting rational numbers on a number line: using fractions like 1/2, 1/5, and 1/7.
  • Plotting irrational numbers on a number line: starting with 1, then using square roots like √2, √3, √5, and √7.
  • Method for plotting irrational numbers using a spiral method.
  • Explanation of why the height of the right angle triangle is always 1 when plotting irrational numbers.
  • Operations on real numbers: rational plus irrational is always irrational, while the result of two irrational numbers can be rational or irrational.
  • Explanation of using 1 as the height in plotting irrational numbers for ease of construction.
  • Expanding expressions using the formulas for (a + b)Β² and (a - b)Β² to find the correct answer.

29:19

Exponents, Rationalization, and Recurring Decimals Explained

  • Non-terminating decimals can be recurring or non-recurring, with recurring decimals being rational and non-recurring decimals being irrational.
  • The square of root 3 is 3, so root 3 squared plus root 3 squared equals 6.
  • Rationalization involves multiplying and dividing by the conjugate of the denominator.
  • Rationalizing 4 plus root 3 divided by 7 plus root 3 involves multiplying by 7 minus root 3 and dividing by 7 minus root 3.
  • Laws of exponents include rules like a to the power m multiplied by a to the power n equals a to the power m plus n.
  • Examples of applying laws of exponents include 2 to the power 3 multiplied by 2 to the power 5 equals 2 to the power 8.
  • Matching identities include a to the power 0 equals 1 and a to the power -m equals 1 divided by a to the power m.
  • Deriving exponent identities involves understanding the concept of multiplying like terms and applying the rules of exponents.
  • Plotting root 6 involves understanding right angle triangles and using the spiral method to visualize the distances.
  • Homework question: 64 to the power 2 by 3 divided by 16 to the power 1 by 2.

43:29

"Equation solving with exponents and Pythagoras"

  • To solve the equation, multiply 4 by 2 raised to the power of 3, focusing on rationalizing the denominator, rules of exponents and powers, and plotting irrational numbers on a number line based on Pythagoras theorem, where the height should always be one and the hypotenuse corresponds to the square root of the desired number.
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