JEE Main & Advanced JEE Main Paper Phase-I (Held on 08-1-2020 Evening)

  • question_answer
    Which of the following statements is a tautology?                            [JEE MAIN Held on 08-01-2020 Evening]

    A) \[\tilde{\ }\left( p\wedge \tilde{\ }q \right)\to p\vee q\]

    B) \[p\vee (~\sim q)\to p\wedge q\]

    C) \[\sim \left( p\vee \tilde{\ }q \right)\to p\vee q\]

    D) \[~\sim (p\vee \sim ~q)\to p\wedge q\]

    Correct Answer: C

    Solution :

    \[\because \,\,\,\,\,\,\,p\to q=q\vee \tilde{\ }P\] \[\therefore \] Checking option \[3\tilde{\ }\left( p\vee -q \right)\to \left( p\vee q \right)\] is equivalent to \[\Rightarrow \,\,\,\,\,\,\left( p\vee q \right)\vee \left( p\vee \tilde{\ }q \right)\] \[\Rightarrow \,\,\,\,\,\,p\vee T\equiv T\]


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