Q62 / 150 · MHT CET 2026 (15 April Shift 1) · Mathematics
The dual of the converse of the inverse of the logical statement $p \to (q \to r)$ is equivalent to...
- Correct answerA$\sim [p \vee (r \to q)]$
- B$p \vee (r \to q)$
- C$\sim [p \vee (q \to r)]$
- D$p \vee (q \to r)$
Solution
The given statement is $p \to (q \to r)$.
The inverse of a conditional statement $A \to B$ is $\sim A \to \sim B$.
The converse of $C \to D$ is $D \to C$.
Thus, the converse of the inverse of $A \to B$ is $\sim B \to \sim A$, which is the contrapositive of the original statement.
For $p \to (q \to r)$, the converse of the inverse is:
$\sim (q \to r) \to \sim p$
We can simplify this using the equivalence $X \to Y \equiv \sim X \vee Y$:
$\sim (q \to r) \to \sim p \equiv (q \to r) \vee \sim p$
$\equiv (\sim q \vee r) \vee \sim p$
$\equiv \sim p \vee \sim q \vee r$
To find the dual of a logical expression, we replace $\vee$ with $\wedge$ and $\wedge$ with $\vee$ (while keeping the literals unchanged).
The dual of $(\sim p \vee \sim q \vee r)$ is $(\sim p \wedge \sim q \wedge r)$.
Now, we check the given options to find which one is equivalent to $\sim p \wedge \sim q \wedge r$.
Evaluating the first option:
$\sim [p \vee (r \to q)] \equiv \sim [p \vee (\sim r \vee q)]$
Using De Morgan's laws:
$\equiv \sim p \wedge \sim (\sim r \vee q)$
$\equiv \sim p \wedge (r \wedge \sim q)$
$\equiv \sim p \wedge \sim q \wedge r$
This matches the dual of the converse of the inverse.
Answer: $\sim [p \vee (r \to q)]$
The inverse of a conditional statement $A \to B$ is $\sim A \to \sim B$.
The converse of $C \to D$ is $D \to C$.
Thus, the converse of the inverse of $A \to B$ is $\sim B \to \sim A$, which is the contrapositive of the original statement.
For $p \to (q \to r)$, the converse of the inverse is:
$\sim (q \to r) \to \sim p$
We can simplify this using the equivalence $X \to Y \equiv \sim X \vee Y$:
$\sim (q \to r) \to \sim p \equiv (q \to r) \vee \sim p$
$\equiv (\sim q \vee r) \vee \sim p$
$\equiv \sim p \vee \sim q \vee r$
To find the dual of a logical expression, we replace $\vee$ with $\wedge$ and $\wedge$ with $\vee$ (while keeping the literals unchanged).
The dual of $(\sim p \vee \sim q \vee r)$ is $(\sim p \wedge \sim q \wedge r)$.
Now, we check the given options to find which one is equivalent to $\sim p \wedge \sim q \wedge r$.
Evaluating the first option:
$\sim [p \vee (r \to q)] \equiv \sim [p \vee (\sim r \vee q)]$
Using De Morgan's laws:
$\equiv \sim p \wedge \sim (\sim r \vee q)$
$\equiv \sim p \wedge (r \wedge \sim q)$
$\equiv \sim p \wedge \sim q \wedge r$
This matches the dual of the converse of the inverse.
Answer: $\sim [p \vee (r \to q)]$
Hence, the correct answer is option: 'A'.