Class 9 · Mathematics · New NCERT
Chapter 9: Propositions and their Converses
Chapter 9 introduces propositions (statements that are true or false) and their converses. Through everyday examples and results from number theory and geometry, such as multiples of 6 and 3, perfect squares and odd numbers of factors, and the Baudhayana-Pythagoras theorem, it shows that a proposition can be true while its converse is false, that both can be true, or that both can be false. It also shows how a counterexample is used to disprove a statement.
Topics covered
- Propositions and 'if X then Y' statements
- The converse of a proposition
- Counterexamples
- Perfect squares and the number of factors
- Converse of the Baudhayana-Pythagoras theorem