JEE Main 2023 (Online) 31st January Morning ShiftQuestion 1
Consider:
S1: $(p\Rightarrow q)\vee(p\wedge\sim q)$ is a tautology.
S2: $(\sim p\Rightarrow\sim q)\wedge(\sim p\vee q)$ is a contradiction.
Then
Sets, Relations and Function
Solution
$p\wedge\sim q\equiv\sim(p\Rightarrow q)$, so S1 is $X\vee\sim X$, a tautology. $(\sim p\Rightarrow\sim q)\wedge(\sim p\vee q)=(p\vee\sim q)\wedge(\sim p\vee q)\equiv p\Leftrightarrow q$, which is not a contradiction. Only S1 is correct.