Maths · Class 12 · Chapter 1
Relations and Functions
10 lessons 99 min 2 simulations
Class XI met relations and functions as sets of ordered pairs. This chapter sorts them by type: relations on a set that are reflexive, symmetric or transitive, the equivalence relations that split a set into classes, and functions that are one-one, onto or both. It ends with composing two functions and with the exact condition for a function to have an inverse, which the next chapter uses to build the inverse trigonometric functions.
What the exam asks
JEE Main tests whether a given relation is reflexive, symmetric, transitive or an equivalence relation, counts relations and functions of a given type on small sets, and asks whether a function is one-one, onto or bijective, often with a changed domain or codomain. Marks are lost by checking one pair instead of all pairs, by forgetting that the codomain decides onto, by writing gof(x) as f(g(x)), and by calling a function invertible when it is only one-one.
Lessons
10 lessons · 99 min
1Empty and universal relationsNCERT §1.29 min2Reflexive, symmetric and transitiveNCERT §1.29 min3Equivalence relationsNCERT §1.212 min 1 sim4Equivalence classesNCERT §1.28 min5One-one functionsNCERT §1.38 min6Onto and bijective functionsNCERT §1.312 min 1 sim7Finite sets and countingNCERT §1.39 min8Composition of functionsNCERT §1.48 min9Invertible functionsNCERT §1.49 min10Chapter reviewMust-know facts, traps and formulas15 min