CEE Kerala Engineering CEE Kerala Engineering Solved Paper-2011

  • question_answer
    The negation of\[(p\vee \tilde{\ }q)\wedge q\]is

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

    B)  \[(p\wedge \tilde{\ }q)\vee q\]

    C)  \[(\tilde{\ }p\wedge q)\vee \tilde{\ }q\]

    D)         \[(p\wedge \tilde{\ }q)\vee \tilde{\ }q\]

    E)  \[(\tilde{\ }p\vee \tilde{\ }q)\wedge \tilde{\ }q\]

    Correct Answer: C

    Solution :

    \[X=(p\vee \tilde{\ }q)\wedge q\]
    \[p\] \[q\] \[\tilde{\ }p\] \[\tilde{\ }q\] \[p\vee \tilde{\ }q\] \[X\] \[(\tilde{\ }p\vee q)\] \[A\] \[(p\wedge \tilde{\ }q)\] \[B\] \[(\tilde{\ }p\wedge q)\] \[C\] \[D\] \[-p\vee \tilde{\ }q\] \[E\] \[\tilde{\ }X\]
    F F T T T F T T F F F T T T T T
    F T T F F F T F F T T T F T F T
    T F F T T F F F F F F T T T T T
    T T F F T T T F F T F F F F F F
    Where  \[A=(\tilde{\ }p\vee q)\wedge \tilde{\ }q\] \[B=(p\wedge \tilde{\ }q)\vee \tilde{\ }q\] \[C=(\tilde{\ }p\wedge q)\vee \tilde{\ }q\] \[D=(p\wedge \tilde{\ }q)\vee \tilde{\ }q\] \[E=(\tilde{\ }p\vee \tilde{\ }q)\wedge \tilde{\ }q\] Here,     \[\tilde{\ }X\equiv C\] i.e.,        \[\tilde{\ }[(p\vee \tilde{\ }q)\wedge q]\equiv (\tilde{\ }p\wedge q)\vee \tilde{\ }q\] Alternate Method                 \[\tilde{\ }[(p\vee \tilde{\ }q)\wedge q]\]                 \[=\tilde{\ }(p\vee \tilde{\ }q)\wedge \tilde{\ }q\]                                 (\[\because \]By De Morgan Law)                 \[=(\tilde{\ }p\wedge \tilde{\ }(\tilde{\ }q))\vee \tilde{\ }q\] (\[\because \]By De Morgan Law) \[=\tilde{\ }(p\wedge q)\vee \tilde{\ }q\]      (\[\because \] By Nagetion)


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