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NCERT Solutions for Exercise 1.2 Class 12 Maths Chapter 1 Relations and Functions are discussed here. These NCERT solutions are created by subject matter expert at Careers360 considering the latest syllabus and pattern of CBSE 2023-24. NCERT Solutions for Class 12 Maths chapter 1 exercise 1.2 is the most important exercise of chapter Relations and Functions and it includes topics like types of relations, functions, binary operations etc. Exercise 1.2 Class 12 Maths exposes students to questions like proving one to one functions etc. Such questions are generally asked in Board examinations. Solving NCERT syllabus for Class 12 Maths chapter 1 exercise 1.2 is recommended to students to score well in CBSE Class 12 board exam. The contribution of chapter Relations and Functions is high in competitive exams also like JEE main and NEET. There are many questions asked in previous years which are based on concepts of Class 12 Maths chapter 1 exercise 1.2.
12th class Maths exercise 1.2 answers are designed as per the students demand covering comprehensive, step by step solutions of every problem. Practice these questions and answers to command the concepts, boost confidence and in depth understanding of concepts. Students can find all NCERT exercise together using the link provided below.
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Answer:
Given, is defined by .
One - One :
f is one-one.
Onto:
We have , then there exists ( Here ) such that
.
Hence, the function is one-one and onto.
If the domain R ∗ is replaced by N with co-domain being same as R ∗ i.e. defined by
g is one-one.
For ,
but there does not exists any x in N.
Hence, function g is one-one but not onto.
Question:2(i) Check the injectivity and surjectivity of the following functions:
Answer:
One- one:
then
f is one- one i.e. injective.
For there is no x in N such that
f is not onto i.e. not surjective.
Hence, f is injective but not surjective.
Question:2(ii) Check the injectivity and surjectivity of the following functions:
Answer:
One- one:
For then
but
f is not one- one i.e. not injective.
For there is no x in Z such that
f is not onto i.e. not surjective.
Hence, f is neither injective nor surjective.
Question:2(iii) Check the injectivity and surjectivity of the following functions:
Answer:
One- one:
For then
but
f is not one- one i.e. not injective.
For there is no x in R such that
f is not onto i.e. not surjective.
Hence, f is not injective and not surjective.
Question:2(iv) Check the injectivity and surjectivity of the following functions:
Answer:
One- one:
then
f is one- one i.e. injective.
For there is no x in N such that
f is not onto i.e. not surjective.
Hence, f is injective but not surjective.
Question:2(v) Check the injectivity and surjectivity of the following functions:
Answer:
One- one:
For then
f is one- one i.e. injective.
For there is no x in Z such that
f is not onto i.e. not surjective.
Hence, f is injective but not surjective.
Answer:
One- one:
For then and
but
f is not one- one i.e. not injective.
For there is no x in R such that
f is not onto i.e. not surjective.
Hence, f is not injective but not surjective.
Answer:
One- one:
For then
f is not one- one i.e. not injective.
For ,
We know is always positive there is no x in R such that
f is not onto i.e. not surjective.
Hence, , is neither one-one nor onto.
Question:5 Show that the Signum Function , given by
Answer:
is given by
As we can see , but
So it is not one-one.
Now, f(x) takes only 3 values (1,0,-1) for the element -3 in codomain ,there does not exists x in domain such that .
So it is not onto.
Hence, signum function is neither one-one nor onto.
Question:6 Let , and let be a function from A to B. Show that f is one-one.
Answer:
Every element of A has a distant value in f.
Hence, it is one-one.
Question:7(i) In each of the following cases, state whether the function is one-one, onto or bijective. Justify your answer.
Answer:
Let there be such that
f is one-one.
Let there be ,
Puting value of x,
f is onto.
f is both one-one and onto hence, f is bijective.
Question:7(ii) In each of the following cases, state whether the function is one-one, onto or bijective. Justify your answer.
Answer:
Let there be such that
For and
f is not one-one.
Let there be (-2 in codomain of R)
There does not exists any x in domain R such that
f is not onto.
Hence, f is neither one-one nor onto.
Question:8 Let A and B be sets. Show that such that is
bijective function.
Answer:
Let
such that
and
f is one- one
Let,
then there exists such that
f is onto.
Hence, it is bijective.
Question:9 Let be defined by for all . State whether the function f is bijective. Justify your answer.
Answer:
,
Here we can observe,
and
As we can see but
f is not one-one.
Let, (N=co-domain)
case1 n be even
For ,
then there is such that
case2 n be odd
For ,
then there is such that
f is onto.
f is not one-one but onto
hence, the function f is not bijective.
Question:10 Let and . Consider the function defined by . Is f one-one and onto? Justify your answer.
Answer:
Let such that
f is one-one.
Let, then
such that
For any there exists such that
f is onto
Hence, the function is one-one and onto.
Question:11 Let be defined as . Choose the correct answer.
(D) f is neither one-one nor onto.
Answer:
One- one:
For then
does not imply that
example: and
f is not one- one
For there is no x in R such that
f is not onto.
Hence, f is neither one-one nor onto.
Option D is correct.
Question:12 Let be defined as . Choose the correct answer.
(D) f is neither one-one nor onto.
Answer:
One - One :
Let
f is one-one.
Onto:
We have , then there exists such that
.
Hence, the function is one-one and onto.
The correct answer is A .
The NCERT Class 12 Maths chapter Relations and Functions has a total of 5 exercises including miscellaneous. Exercise 1.2 Class 12 Maths covers solutions to 12 main questions and their sub-questions. Most of the questions are related to proving a function one to one. Hence NCERT Solutions for Class 12 Maths chapter 1 exercise 1.2 can be referred for learning the concepts related to proof etc.
Also Read| NCERT Notes For Class 12 Mathematics Chapter 1
NCERT Solutions Subject Wise
Subject wise NCERT Exemplar solutions
Happy learning!!!
Concepts related to one to one functions, reflexive functions etc, are discussed in the Exercise 1.2 Class 12 Maths
In Mathematics, A set is a collection of distinct or well-defined numbers or elements
Weightage of the chapters 'relation and function' is around 5 % weightage in the CBSE final board exam.
There are 3 ways to represent a set:
a. Statement form.
b. Roaster form .
c. Set Builder form.
A set with no elements is called an empty set. Also known by Null set or void set.
A relation is the set of ordered pair numbers.
12 questions are there in Exercise 1.2 Class 12 Maths
5 exercises are there including a miscellaneous exercise in the NCERT class 12 maths chapter 1.
You can use them people also used problem
hello mahima,
If you have uploaded screenshot of your 12th board result taken from CBSE official website,there won,t be a problem with that.If the screenshot that you have uploaded is clear and legible. It should display your name, roll number, marks obtained, and any other relevant details in a readable forma.ALSO, the screenshot clearly show it is from the official CBSE results portal.
hope this helps.
Hello Akash,
If you are looking for important questions of class 12th then I would like to suggest you to go with previous year questions of that particular board. You can go with last 5-10 years of PYQs so and after going through all the questions you will have a clear idea about the type and level of questions that are being asked and it will help you to boost your class 12th board preparation.
You can get the Previous Year Questions (PYQs) on the official website of the respective board.
I hope this answer helps you. If you have more queries then feel free to share your questions with us we will be happy to assist you.
Thank you and wishing you all the best for your bright future.
Hello student,
If you are planning to appear again for class 12th board exam with PCMB as a private candidate here is the right information you need:
Remember
, these are tentative dates based on last year. Keep an eye on the CBSE website ( https://www.cbse.gov.in/ ) for the accurate and official announcement.
I hope this answer helps you. If you have more queries then feel free to share your questions with us, we will be happy to help you.
Good luck with your studies!
Hello Aspirant , Hope your doing great . As per your query , your eligible for JEE mains in the year of 2025 , Every candidate can appear for the JEE Main exam 6 times over three consecutive years . The JEE Main exam is held two times every year, in January and April.
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