Concept-wise Practice

proof idea MCQ Questions for Class 10

proof idea se related questions ko ek jagah revise karein. Har question me bilingual content, answer feedback aur explanation available hai.

Practice Questions

2 questions tagged with proof idea.

Question 1/2 Expert Mathematics Chapter 1: Real Numbers 5: Irrational numbers Class 10 Level 13

कौन-सा विकल्प बताता है कि \(\sqrt{2}+\sqrt{3}\) अपरिमेय है?

Which option explains why \(\sqrt{2}+\sqrt{3}\) is irrational?

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Correct Answer

A. यदि यह परिमेय हो, तो वर्ग करने पर \(5+2\sqrt{6}\) परिमेय होगा और \(\sqrt{6}\) परिमेय निकल आएगाIf it were rational, squaring would make \(5+2\sqrt{6}\) rational and then \(\sqrt{6}\) would be rational

Step 1

Concept

Assume \(\sqrt{2}+\sqrt{3}\) is rational.

Step 2

Why this answer is correct

Squaring gives \(5+2\sqrt{6}\) rational, which would force \(\sqrt{6}\) to be rational, impossible.

Step 3

Exam Tip

Squaring is useful for sums of two different surds. चरण 1: मान लें \(\sqrt{2}+\sqrt{3}\) परिमेय है। चरण 2: वर्ग करने पर \(5+2\sqrt{6}\) परिमेय होगा, जिससे \(\sqrt{6}\) परिमेय मानना पड़ेगा, जो गलत है। चरण 3: दो अलग मूलों के योग में वर्ग विधि उपयोगी होती है।

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Question 2/2 Hard Mathematics Chapter 1: Real Numbers 5: Irrational numbers Class 10 Level 14

यदि (x) अपरिमेय है, तो (x+3) के परिमेय होने की संभावना के बारे में सही कथन क्या है?

If (x) is irrational, what is correct about the possibility of (x+3) being rational?

Explanation opens after your attempt
Correct Answer

B. यह कभी परिमेय नहीं हो सकताIt can never be rational

Step 1

Concept

(3) is rational.

Step 2

Why this answer is correct

If (x+3) were rational, then (x=(x+3)-3) would also be rational, contradicting the given fact.

Step 3

Exam Tip

The contradiction method is useful in such questions. चरण 1: (3) एक परिमेय संख्या है। चरण 2: यदि (x+3) परिमेय हो, तो (x=(x+3)-3) भी परिमेय होगा, जो दी गई बात के विरुद्ध है। चरण 3: ऐसे प्रश्नों में विरोध विधि तेज काम करती है।

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