Last updated at May 29, 2018 by Teachoo

Transcript

Ex1.5, 3 Recall, is defined as the ratio of the circumference (say c) of a circle to its diameter (say d). That is, = / . This seems to contradict the fact that is irrational. How will you resolve this contradiction? = / is a rational number when c & d both are rational numbers But the c & d we calculate is not exactly a rational number and either c or d or both can be irrational numbers, Since, / = Irrational So, is irrational.

Chapter 1 Class 9 Number Systems

Concept wise

- Rational numbers - Definition
- Finding rational number between two numbers
- Irrational Numbers
- Simplifying real numbers
- Rationalising
- Laws of exponents
- Finding decimal expansion
- Expressing decimal in p/q
- Classifiying rational/irrational
- Finding irrational numbers b/w two numbers
- Real numbers on a number line

About the Author

Davneet Singh

Davneet Singh is a graduate from Indian Institute of Technology, Kanpur. He has been teaching from the past 9 years. He provides courses for Maths and Science at Teachoo.