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Class 12 Maths Mcqs

Q:

Let R be a relation in the set N given by R={(a,b): a+b=5, b>1}. Which of the following will satisfy the given relation?

A) (2,3) ? R B) (4,2) ? R
C) (2,1) ? R D) (5,0) ? R
 
Answer & Explanation Answer: A) (2,3) ? R

Explanation: (2,3) ? R as 2+3 = 5, 3>1, thus satisfying the given condition.
(4,2) doesn’t belong to R as 4+2 ? 5.
(2,1) doesn’t belong to R as 2+1 ? 5.
(5,0) doesn’t belong to R as 0?1

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Sub Category: Class 12 Maths Mcqs

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Q:

Which of the following relations is transitive but not reflexive for the set S={3, 4, 6}?

A) R = {(3, 4), (4, 6), (3, 6)} B) R = {(1, 2), (1, 3), (1, 4)}
C) R = {(3, 3), (4, 4), (6, 6)} D) R = {(3, 4), (4, 3)}
 
Answer & Explanation Answer: A) R = {(3, 4), (4, 6), (3, 6)}

Explanation: For the above given set S = {3, 4, 6}, R = {(3, 4), (4, 6), (3, 6)} is transitive as (3,4)?R and (4,6) ?R and (3,6) also belongs to R . It is not a reflexive relation as it does not satisfy the condition (a,a)?R, for every a?A for a relation R in the set A.

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Sub Category: Class 12 Maths Mcqs

75
Q:

Which of the following relations is symmetric but neither reflexive nor transitive for a set A = {1, 2, 3}.

A) R = {(1, 2), (1, 3), (1, 4)} B) R = {(1, 2), (2, 1)}
C) R = {(1, 1), (2, 2), (3, 3)} D) R = {(1, 1), (1, 2), (2, 3)}
 
Answer & Explanation Answer: B) R = {(1, 2), (2, 1)}

Explanation: A relation in a set A is said to be symmetric if (a?, a?)?R implies that (a?, a?)?R,for every a?, a??R.
Hence, for the given set A={1, 2, 3}, R={(1, 2), (2, 1)} is symmetric. It is not reflexive since every element is not related to itself and neither transitive as it does not satisfy the condition that for a given relation R in a set A if (a?, a?)?R and (a?, a?)?R implies that (a?, a?)? R for every a?, a?, a??R.

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Category: School MCQs
Sub Category: Class 12 Maths Mcqs

121
Q:

An Equivalence relation is always symmetric.

A) True B) False
 
Answer & Explanation Answer: A) True

Explanation: The given statement is true. A relation R in a set A is said to be an equivalence relation if R is reflexive, symmetric and transitive. Hence, an equivalence relation is always symmetric.

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Category: School MCQs
Sub Category: Class 12 Maths Mcqs

59
Q:

Which of these is not a type of relation?

A) Reflexive B) Surjective
C) Symmetric D) Transitive
 
Answer & Explanation Answer: B) Surjective

Explanation: Surjective is not a type of relation. It is a type of function. Reflexive, Symmetric and Transitive are type of relations.

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Sub Category: Class 12 Maths Mcqs

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