Mathematical Reasoning
medium

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?

A

$(a)$ and $(b)$ both are not tautologies.

B

$(a)$ and $(b)$ both are tautologies.

C

$(a)$ is a tautology but not $(b).$

D

$(b)$ is a tautology but not $(a).$

(JEE MAIN-2021)

Solution

$(A)$

$p$ $q$ $\sim q$ $p \rightarrow q$ $\sim p$ $(\sim q \wedge( p \rightarrow q ))$  
$T$ $T$ $F$ $T$ $F$ $F$ $T$
$T$ $F$ $T$ $F$ $F$ $F$ $T$
$F$ $T$ $F$ $T$ $T$ $F$ $T$
$F$ $F$ $T$ $T$ $T$ $T$ $T$

$(B)$

$p$ $q$ $p \vee q$ $\sim p$ $(p \vee q) \wedge \sim p$  
$T$ $T$ $T$ $F$ $F$ $T$
$T$ $F$ $T$ $F$ $F$ $T$
$F$ $T$ $T$ $T$ $T$ $T$
$F$ $F$ $F$ $T$ $F$ $T$

Both are tautologies   

Standard 11
Mathematics

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