Skip to content
Question of 45

Q.Verify by the method of contradiction p:7p : \sqrt{7} is irrational.

Bihar BsebBihar Board Intermediate 1st Year 2023Subjective· 2mImportance★★★★★
0% · 0/45 Questions
🔒 Locked · start free trial →

You're viewing a preview — the full solution, concept, methods & PYQ mapping are locked.

Start your 14-day free trial to unlock the full solution →

7\sqrt7 is irrational, by contradiction.

Suppose, for contradiction, that p:7p:\sqrt7 is rational (NCERT Class 11 Mathematical Reasoning, method of contradiction). Then 7=pq\sqrt7=\dfrac pq for integers p,qp,q with no common factor and qe0q e0.

Squaring: 7=p2q2⇒p2=7q2.7=\dfrac{p^2}{q^2}\Rightarrow p^2=7q^2. So 7∣p27\mid p^2, hence 7∣p7\mid p. Write p=7kp=7k:

…

Unlock everything free for 14 days

  • Full step-by-step solutions
  • Concept-first explanations
  • Methods, shortcuts & mistakes
  • PYQ mapping + timed mock tests

Full access for 14 days. No credit card required.