Class 12 Mathematics - Relations and Functions - Onto function Expert Quiz

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\(मान लें (A={1,2,3,4,5}) और (R={(a,b)\in A\times A:a+b\) सम है})। इस संबंध को प्रतिवर्ती बनाने के लिए कम-से-कम कितने युग्म जोड़ने होंगे?

\(Let (A={1,2,3,4,5}) and (R={(a,b)\in A\times A:a+b\) is even}). What is the minimum number of ordered pairs that must be added to make this relation reflexive?

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Correct Answer

B. 2

Step 1

Concept

A reflexive relation needs every ((a,a)) for \(a\in A\).

Step 2

Why this answer is correct

Since (a+a=2a) is always even, every diagonal pair is already present.

Step 3

Exam Tip

The exam trick is to check diagonal pairs first, not the whole relation. चरण 1: प्रतिवर्ती संबंध के लिए हर \(a\in A\) पर \((a,a)\in R\) होना चाहिए। चरण 2: ((a,a)) में (a+a=2a) हमेशा सम होता है, इसलिए सभी विकर्ण युग्म पहले से हैं। चरण 3: ध्यान से देखें कि यहां कोई युग्म जोड़ने की जरूरत नहीं है।

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यदि \(A=\{1,2,3,4\}\) और \(R=\{(a,b):\min(a,b)=a\}\) है, तो (R) कैसा है?

If \(A=\{1,2,3,4\}\) and \(R=\{(a,b):\min(a,b)=a\}\), what is (R) with respect to reflexivity?

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Correct Answer

A. प्रतिवर्तीReflexive

Step 1

Concept

On the diagonal, (\min(a,a)=a).

Step 2

Why this answer is correct

This is true for every \(a\in A\), so all ((a,a)) are in the relation.

Step 3

Exam Tip

For minimum and maximum conditions, substitute equal elements first. चरण 1: विकर्ण पर (\min(a,a)=a) होता है। चरण 2: यह हर \(a\in A\) के लिए सत्य है, इसलिए सभी ((a,a)) संबंध में हैं। चरण 3: न्यूनतम और अधिकतम वाले संबंधों में समान तत्व रखकर तुरंत जांचें।

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समुच्चय \(A=\{1,2,3,4\}\) पर \(R=\{(a,b):\max(a,b)=b\}\) है। सही निष्कर्ष कौन-सा है?

On \(A=\{1,2,3,4\}\), \(R=\{(a,b):\max(a,b)=b\}\). Which conclusion is correct?

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Correct Answer

A. (R) प्रतिवर्ती है(R) is reflexive

Step 1

Concept

For ((a,a)), (\max(a,a)=a).

Step 2

Why this answer is correct

Since (b=a) on the diagonal, (\max(a,a)=b) is true.

Step 3

Exam Tip

Reflexivity only needs the same-element cases to hold. चरण 1: ((a,a)) पर (\max(a,a)=a) होता है। चरण 2: यहां (b=a) है, इसलिए (\max(a,a)=b) भी सत्य है। चरण 3: प्रतिवर्तिता में केवल समान तत्वों की शर्त जरूरी है।

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