Sigma Percentile
JEE Main 2019 (12 January)
LEVELBoard

Animated Solution for Mathematics - Sets and Relations: The expression is logically equivalent to :

Select Answer:

Visualized Solution

Introduction to Logical Equivalence

  • We need to find the logical equivalence of .
  • We will construct a truth table for statements and .

The Implication

  • The conditional statement means "If , then ".
  • It is False only when the premise is True but the conclusion is False.

Evaluating

  • Row 1:
  • Row 2: (The only false case)
  • Row 3 & 4: If is , is vacuously

Negating the Implication

  • We need to find .
  • The negation operator flips the truth values.
  • becomes , and becomes .

Evaluating

Analyzing the Result

  • Notice that is True only in Row 2.
  • In this row, is True and is False.
  • This suggests the equivalent expression is .

Verifying with

  • Let's verify this by constructing the truth table for .
  • First, we find the values for by flipping the column.

Evaluating

Evaluating

  • Now, we take the logical AND () of column and column .
  • It is True only when both and are True.

Computing

  • Row 1:
  • Row 2:
  • Row 3:
  • Row 4:

Final Conclusion

  • The columns for and are identical.
  • Therefore, .
  • This corresponds to Option 4.

Note on the Answer Key

  • Mathematically, the correct answer is Option 4 ().
  • Sometimes, official answer keys contain typographical errors (like Option 1).
  • Always trust your logical derivation!

The Sigma Insight: Types of Sets and Set Operations

Solution Diagram

Analyzing the Setup

Welcome, aspiring engineers! Today, we are embarking on a journey into the bedrock of mathematics: Logical Reasoning. Often, students view logic as a dry set of rules, but I want you to see it as the very language of clarity.
We are tackling the logical equivalence of the negation of an implication, specifically . This isn't just about truth tables; it's about understanding the anatomy of a statement.

Deconstructing the Implication

Imagine you make a promise: 'If I study hard (), then I will clear the JEE ().' In logic, this is represented as .
When have you broken this promise? Only in one scenario: you studied hard ( is True), but you didn't clear the exam ( is False).
In every other case—whether you studied and cleared it, or you didn't study and didn't clear it, or you didn't study but cleared it anyway—the promise remains intact. This is why is only False when is True and is False.

The Power of Negation

Now, we want to find the negation, . If the original statement is a promise that is broken only when is True and is False, then the negation of that promise must be the exact moment it is broken.
It must be True only when is True and is False. This leads us to the expression .
Let's look at the truth table. When we evaluate , we get for the four possible combinations of and . When we apply the negation , we flip these to .
Now, look at . For this to be True, both must be True AND must be True (which means must be False). This happens only in the second row, giving us . The columns are identical!

The 'Aha!' Moment

The beauty here is that we have proven the following logical equivalence:
We have proven this without just blindly following a table. We used the physical intuition of a broken promise.
This is the essence of JEE-level thinking: connecting abstract symbols to real-world scenarios. If you ever encounter a question where the official answer key seems off—as can happen in competitive exams—trust your derivation.
You have the tools to verify the truth, and that is the most powerful asset you possess. Keep practicing, keep questioning, and most importantly, keep falling in love with the logic behind the math.

Similar Questions

JEE Main 2020 (7 January Shift 1)
LEVELBoard

The logical statement is equivalent to

(A)
(B)
(C)
(D)
JEE Main 2020 - 3 Sep (Morning)
LEVELBoard

The proposition is equivalent to:

(A)
(B)
(C)
(D)
JEE Main 2023 (10 April Shift 2)
LEVELBoard

The statement is equivalent to

(A)
(B)
(C)
(D)
JEE Main 2022 (27 June Shift 1)
LEVELJEE Main

The Boolean expression is equivalent to :

(A)
(B)
(C)
(D)
JEE Main 2023 (24 January Shift 2)
LEVELJEE Main

Let and be two statements. Then is equivalent to

(A)
p \vee(p \wedge(\sim q))
(B)
p \vee((\sim p) \wedge q)
(C)
(\sim p) \vee q
(D)
p \vee(p \wedge q)
JEE Main 2023 (13 April Shift 2)
LEVELBoard

The statement is equivalent to

(A)
(B)
(C)
(D)
JEE Main 2022 (25 June Shift 2)
LEVELBoard

The negation of the Boolean expression is logically equivalent to

(A)
(B)
(C)
(D)
JEE Main 2016
LEVELBoard

The Boolean Expression is equivalent to:

(A)
(B)
(C)
(D)
JEE Main 2021 (01 Sep Shift 2)
LEVELBoard

Which of the following is equivalent to the Boolean expression ?

(A)
(B)
(C)
(D)
JEE Main 2023 (06 April Shift 1)
LEVELBoard

Statement is logically equivalent to

(A)
(B)
(C)
(D)