Which of following Boolean expressions is not a tautology ?

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Mathematical Reasoning

medium

Which of the following Boolean expressions is not a tautology ?

$(\sim \mathrm{p} \Rightarrow \mathrm{q}) \vee(\sim \mathrm{q} \Rightarrow p)$

$(\mathrm{q} \Rightarrow p) \vee(\sim \mathrm{q} \Rightarrow p)$

$(\mathrm{p} \Rightarrow \mathrm{q}) \vee(\sim \mathrm{q} \Rightarrow p)$

$(\mathrm{p} \Rightarrow \sim \mathrm{q}) \vee(\sim \mathrm{q} \Rightarrow p)$

(JEE MAIN-2021)

Solution

$(1)(\sim p \rightarrow q) \vee(\sim q \rightarrow p)$

$=(p \vee q) \vee(q \vee p)$

$=(p \vee p) \vee(q \vee q)$

$= \mathrm{p} \vee \mathrm{q}$

Which is not a tautology.

$(2)(q \rightarrow p) \vee(\sim q \rightarrow p)$

$=(\sim q \vee p) \vee(q \vee p)$

$=(\sim q \vee q) \vee p$

$= t \vee p=t$

$(3)(p \rightarrow q) \vee(\sim q \rightarrow p)$

$=(\sim p \vee q) \vee(q \vee p)$

$=(\sim p \vee p) \vee q$

$= t \vee q=t$

$(4)(p \rightarrow \sim q) \vee(\sim q \rightarrow p)$

$=(\sim p \vee \sim q) \vee(q \vee p)$

$=(\sim p \vee q) \vee(\sim q \vee q)$

$= t \vee t=t$

Standard 11

Mathematics

For the statements $p$ and $q$, consider the following compound statements :

$(a)$ $(\sim q \wedge( p \rightarrow q )) \rightarrow \sim p$

$(b)$ $((p \vee q) \wedge \sim p) \rightarrow q$

Then which of the following statements is correct?

medium

(JEE MAIN-2021)

The number of values of $r \in\{p, q, \sim p , \sim q \}$ for which $((p \wedge q) \Rightarrow(r \vee q)) \wedge((p \wedge r) \Rightarrow q)$ is a tautology, is:

hard

(JEE MAIN-2023)

The Boolean Expression $\left( {p\;\wedge \sim q} \right)\;\;\vee \;q\;\;\vee \left( { \sim p\wedge q} \right)$ is equivalent to:

medium

(JEE MAIN-2016)

Which Venn diagram represent the truth of the statement“All students are hard working.”

Where $U$ = Universal set of human being, $S$ = Set of all students, $H$ = Set of all hard workers.

easy

The converse of the statement $((\sim p) \wedge q) \Rightarrow r$ is

hard

(JEE MAIN-2023)

Which of the following Boolean expressions is not a tautology ?

Solution

Similar Questions

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The number of values of $r \in\{p, q, \sim p , \sim q \}$ for which $((p \wedge q) \Rightarrow(r \vee q)) \wedge((p \wedge r) \Rightarrow q)$ is a tautology, is:

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For the statements $p$ and $q$, consider the following compound statements :

$(a)$ $(\sim q \wedge( p \rightarrow q )) \rightarrow \sim p$

$(b)$ $((p \vee q) \wedge \sim p) \rightarrow q$

Then which of the following statements is correct?

Which Venn diagram represent the truth of the statement“All students are hard working.”

Where $U$ = Universal set of human being, $S$ = Set of all students, $H$ = Set of all hard workers.