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header-bg qa

Which one of the following Boolean expressions is a tautology?

  • Option 1)

    (p\wedge q)\vee (p\wedge \sim q)

  • Option 2)

    (p\vee q)\vee (p\vee \sim q)

  • Option 3)

    (p\vee q)\wedge (p\vee \sim q)

  • Option 4)

    (p\vee q)\wedge (\sim p\vee \sim q)

 

Answers (1)

1.) (p\wedge q)\vee (p\wedge \sim q) \equivp\wedge (q\vee \sim q)\equiv p\wedge t\equiv p (p\vee q)\wedge \sim (p\wedge q) 

2.) (p\vee q)\wedge ( p\vee \sim q)\equivp\vee (q\vee \sim q)\equiv p\vee t\equiv t

3.) (p\vee q)\wedge (p\vee \sim q)\equivp\vee (q\vee \sim q)\equiv p\vee f\equiv p

not tautology (take both p & q as T )

4.) (p\vee q)\wedge ( \sim p\vee \sim q)\equiv(p\vee q)\wedge \sim (p\wedge q)\rightarrow

not tautology (take both p & q as T )

So, option (2) is correct.


Option 1)

(p\wedge q)\vee (p\wedge \sim q)

Option 2)

(p\vee q)\vee (p\vee \sim q)

Option 3)

(p\vee q)\wedge (p\vee \sim q)

Option 4)

(p\vee q)\wedge (\sim p\vee \sim q)

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Vakul

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