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NCERT Solutions for miscellaneous exercise chapter 1 class 12 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 miscellaneous exercise discusses concepts related to inverse, injective, onto functions. Also in Class 12 maths chapter 1 miscellaneous exercise some of the topics of binary operations signum function, inverse functions. All in all it can be said that in miscellaneous exercises, diverse questions are asked unlike in earlier exercises of this chapter. Hence class 12 maths chapter 1 miscellaneous exercise is a good source to cover the syllabus in a comprehensive manner. There are a total of 5 exercises in the NCERT solutions for class 12 maths chapter 1 including miscellaneous exercise which is present in NCERT Class 12th book. Also with NCERT questions, students should practice NCERT exemplar and class 12 CBSE previous year questions for better understanding.
Miscellaneous exercise class 12 chapter 1 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 exercise enumerated in NCERT Book together using the link provided below.
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NCERT solutions for Class 12 Maths Chapter 1 Relations and Functions: Miscellaneous Exercise
Answer:
and
For one-one:
Thus, f is one-one.
For onto:
For ,
Thus, for , there exists such that
Thus, f is onto.
Hence, f is one-one and onto i.e. it is invertible.
Let as
and
Hence, defined as
Answer:
if n is odd
if n is even.
For one-one:
Taking x as odd number and y as even number.
Now, Taking y as odd number and x as even number.
This is also impossible.
If both x and y are odd :
If both x and y are even :
f is one-one.
Onto:
Any odd number 2r+1 in codomain of N is an image of 2r in domain N and any even number 2r in codomain N is the image of 2r+1 in domain N.
Thus, f is onto.
Hence, f is one-one and onto i.e. it is invertible.
Sice, f is invertible.
Let as if m is even and if m is odd.
When x is odd.
When x is even
Similarly, m is odd
m is even ,
and
Hence, f is invertible and the inverse of f is g i.e. , which is the same as f.
Hence, inverse of f is f itself.
Question:3 If f : R → R is defined by f(x) = x 2 – 3x + 2, find f (f (x)).
Answer:
This can be solved as following
f : R → R
Question:4 Show that the function defined by is one one and onto function.
Answer:
The function defined by
,
One- one:
Let ,
It is observed that if x is positive and y is negative.
Since x is positive and y is negative.
but 2xy is negative.
Thus, the case of x is positive and y is negative is removed.
Same happens in the case of y is positive and x is negative so this case is also removed.
When x and y both are positive:
When x and y both are negative :
f is one-one.
Onto:
Let such that
If y is negative, then
If y is positive, then
Thus, f is onto.
Hence, f is one-one and onto.
Question:5 Show that the function given by is injective.
Answer:
One-one:
Let
We need to prove .So,
Let then there cubes will not be equal i.e. .
It will contradict given condition of cubes being equal.
Hence, and it is one -one which means it is injective
Question:6 Give examples of two functions and such that is injective but g is not injective. (Hint : Consider and ).
Answer:
One - one:
Since
As we can see but so is not one-one.
Thus , g(x) is not injective.
Let
Since, so x and y are both positive.
Hence, gof is injective.
Question:7 Give examples of two functions and such that is onto but is not onto.
Answer:
and
and
Onto :
Consider element in codomain N . It is clear that this element is not an image of any of element in domain N .
f is not onto.
Now, it is clear that , there exists such that .
Hence, is onto.
Answer:
Given a non empty set X, consider P(X) which is the set of all subsets of X.
Since, every set is subset of itself , ARA for all
R is reflexive.
Let
This is not same as
If and
then we cannot say that B is related to A.
R is not symmetric.
If
this implies
R is transitive.
Thus, R is not an equivalence relation because it is not symmetric.
Answer:
Given is defined as .
As we know that
Hence, X is the identity element of binary operation *.
Now, an element is invertible if there exists a ,
such that (X is identity element)
i.e.
This is possible only if .
Hence, X is only invertible element in with respect to operation *
Question:10 Find the number of all onto functions from the set to itself.
Answer:
The number of all onto functions from the set to itself is permutations on n symbols 1,2,3,4,5...............n.
Hence, permutations on n symbols 1,2,3,4,5...............n = n
Thus, total number of all onto maps from the set to itself is same as permutations on n symbols 1,2,3,4,5...............n which is n.
Question:11(i) Let and . Find of the following functions F from S to T, if it exists.
(i)
Answer:
is defined as
is given by
Question:11(ii) Let and . Find of the following functions F from S to T, if it exists.
(ii)
Answer:
is defined as
, F is not one-one.
So inverse of F does not exists.
Hence, F is not invertible i.e. does not exists.
Answer:
Given and is defined as
and
For , we have
the operation is commutative.
where
the operation is not associative
Let . Then we have :
Hence,
Now,
for
Hence, operation o does not distribute over operation *.
Question:13 Given a non-empty set X, let ∗ : P(X) × P(X) → P(X) be defined as A * B = (A – B) ∪ (B – A), ∀ A, B ∈ P(X). Show that the empty set φ is the identity for the operation ∗ and all the elements A of P(X) are invertible with A–1 = A. (Hint : (A – φ) ∪ (φ – A) = A and (A – A) ∪ (A – A) = A ∗ A = φ).
Answer:
It is given that
be defined as
Now, let .
Then,
And
Therefore,
Therefore, we can say that is the identity element for the given operation *.
Now, an element A P(X) will be invertible if there exists B P(X) such that
Now, We can see that
such that
Therefore, by this we can say that all the element A of P(X) are invertible with
Question:14 Define a binary operation ∗ on the set as Show that zero is the identity for this operation and each element of the set is invertible with being the inverse of .
Answer:
X = as
An element is identity element for operation *, if
For ,
Hence, 0 is identity element of operation *.
An element is invertible if there exists ,
such that i.e.
means or
But since we have X = and . Then .
is inverse of a for .
Hence, inverse of element , is 6-a i.e. ,
Question:15 Let , and be functions defined by and . Are and equal? Justify your answer. (Hint: One may note that two functions and such that , are called equal functions).
Answer:
Given :
,
are defined by and .
It can be observed that
Hence, f and g are equal functions.
Question:16 Let . Then number of relations containing and which are reflexive and symmetric but not transitive is
(A) 1
(B) 2
(C) 3
(D) 4
Answer:
The smallest relations containing and which are
reflexive and symmetric but not transitive is given by
, so relation R is reflexive.
and , so relation R is symmetric.
but , so realation R is not transitive.
Now, if we add any two pairs and to relation R, then relation R will become transitive.
Hence, the total number of the desired relation is one.
Thus, option A is correct.
Question:17 Let . Then number of equivalence relations containing is
(A) 1
(B) 2
(C) 3
(D) 4
Answer:
The number of equivalence relations containing is given by
We are left with four pairs , , .
, so relation R is reflexive.
and , so relation R is not symmetric.
, so realation R is not transitive.
Hence , equivalence relation is bigger than R is universal relation.
Thus the total number of equivalence relations cotaining is two.
Thus, option B is correct.
Question:18 Let be the Signum Function defined as and be the Greatest Integer Function given by , where is greatest integer less than or equal to . Then, does and coincide in ?
Answer:
is defined as
is defined as
Let
Then we have , if x=1 and
Hence,for , and .
Hence , gof and fog do not coincide with .
Question:19 Number of binary operations on the set are(A) 10(B) 16(C) 20(D ) 8
Answer:
Binary operations on the set are is a function from
i.e. * is a function from
Hence, the total number of binary operations on set is
Hence, option B is correct
More About NCERT Solutions for Class 12 Maths Chapter 1 Miscellaneous Exercise
The NCERT Class 12 Maths chapter Relations and Functions has a total of 5 exercises including miscellaneous exercise. NCERT solutions for Class 12 Maths chapter 1 miscellaneous exercise covers solutions to 19 main questions and their sub-questions. This exercise covers more NCERT syllabus topics than preceding exercises and holds more weightage for exams also. Hence NCERT solutions for Class 12 Maths chapter 1 miscellaneous exercise is recommended for students to strengthen their conceptual understanding.
Also Read| NCERT Notes For Class 12 Mathematics Chapter 1
Benefits of NCERT Solutions for Class 12 Maths Chapter 1 Miscellaneous Exercises
NCERT Solutions Subject Wise
Happy learning!!!
This exercise discusses concepts related to inverse, injective, onto functions.
Definitions of relations and functions, types of relations, types of functions, composition of functions, invertible function and binary operations are the important topics in this chapter.
The weightage of chapter relation and function is more than 5% in the CBSE board examination.
As students can assess from previous year questions that many questions are asked directly from NCERT exercise. Hence to score well in the examination, it is required to practice NCERT exercise for class 12 maths before the exam.
In maths, relation defines the relationship between sets of values of ordered pairs
Total 19 questions are the in miscellaneous exercise Class 12 Maths chapter 1
There are a total of 5 exercises including a miscellaneous exercise in the NCERT class 12 maths chapter 1.
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Hello there! Thanks for reaching out to us at Careers360.
Ah, you're looking for CBSE quarterly question papers for mathematics, right? Those can be super helpful for exam prep.
Unfortunately, CBSE doesn't officially release quarterly papers - they mainly put out sample papers and previous years' board exam papers. But don't worry, there are still some good options to help you practice!
Have you checked out the CBSE sample papers on their official website? Those are usually pretty close to the actual exam format. You could also look into previous years' board exam papers - they're great for getting a feel for the types of questions that might come up.
If you're after more practice material, some textbook publishers release their own mock papers which can be useful too.
Let me know if you need any other tips for your math prep. Good luck with your studies!
It's understandable to feel disheartened after facing a compartment exam, especially when you've invested significant effort. However, it's important to remember that setbacks are a part of life, and they can be opportunities for growth.
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I hope this information helps you.
Hi,
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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.
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