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JEE Main 2019
Mathematical Reasoning
Mathematical Reasoning
Easy

Question

If p \to (p \wedge ~q) is false, then the truth values of p and q are respectively :

Options

Solution

Key Concepts and Formulas

  • Implication (pqp \to q): The implication pqp \to q is false only when pp is true and qq is false. In all other cases, it is true.
  • Conjunction (pqp \wedge q): The conjunction pqp \wedge q is true only when both pp and qq are true. Otherwise, it is false.
  • Negation (q\sim q): The negation q\sim q is true when qq is false, and false when qq is true.

Step-by-Step Solution

Step 1: Analyze the given statement We are given that p(pq)p \to (p \wedge \sim q) is false.

Step 2: Apply the rule for implication For the implication p(pq)p \to (p \wedge \sim q) to be false, we must have pp as true and (pq)(p \wedge \sim q) as false. This is because pqp \to q is only false when pp is true and qq is false. Therefore, p=Tp = T and (pq)=F(p \wedge \sim q) = F.

Step 3: Apply the rule for conjunction Since pqp \wedge \sim q is false, it means that it is not the case that both pp and q\sim q are true. We already know that pp is true. Therefore, q\sim q must be false.

Step 4: Apply the rule for negation If q\sim q is false, then qq must be true.

Step 5: Summarize the truth values We have p=Tp = T and q=Tq = T.

Common Mistakes & Tips

  • Remember the truth table for implication. The only case where pqp \to q is false is when pp is true and qq is false.
  • Be careful with negation. If q\sim q is false, then qq is true, and vice versa.
  • When dealing with complex logical statements, break them down into smaller parts and analyze each part separately.

Summary

We are given that p(pq)p \to (p \wedge \sim q) is false. This means that pp must be true and pqp \wedge \sim q must be false. Since pp is true, for pqp \wedge \sim q to be false, q\sim q must be false. Therefore, qq must be true. Thus, p=Tp = T and q=Tq = T.

Final Answer The final answer is \boxed{T, T}, which corresponds to option (A).

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