Math Problem Statement

Use the laws to show that -(p^q) v (p^q) = -p

Solution

We are tasked with showing that the expression (pq)(pq)-(p \land q) \lor (p \land q) simplifies to ¬p\neg p. To do this, we'll use some standard logical laws, including De Morgan's Law, Distributive Law, and Absorption Law. Let's break it down step by step.

Expression:

(pq)(pq)-(p \land q) \lor (p \land q)

Step 1: Apply De Morgan's Law

De Morgan's law tells us that: ¬(pq)=¬p¬q\neg (p \land q) = \neg p \lor \neg q So, applying this law to the negation of pqp \land q, we get: (¬p¬q)(pq)(\neg p \lor \neg q) \lor (p \land q)

Step 2: Distribute ¬p¬q\neg p \lor \neg q over (pq)(p \land q)

Now, apply the Distributive Law: (¬p¬q)(pq)=(¬p(pq))(¬q(pq))(\neg p \lor \neg q) \lor (p \land q) = (\neg p \lor (p \land q)) \lor (\neg q \lor (p \land q)) We will handle both parts separately.

Step 3: Simplify using Absorption Law

Let’s simplify ¬p(pq)\neg p \lor (p \land q) first. By Absorption Law, we know: ¬p(pq)=¬p\neg p \lor (p \land q) = \neg p This is because if ¬p\neg p is true, the entire disjunction is true regardless of pqp \land q; and if ¬p\neg p is false, pqp \land q would be false too.

Now let’s simplify ¬q(pq)\neg q \lor (p \land q). By another application of Absorption Law: ¬q(pq)=p\neg q \lor (p \land q) = p This is because if pqp \land q is true, the whole disjunction is true regardless of ¬q\neg q, and if pqp \land q is false, then the truth of ¬q\neg q determines the value of the disjunction.

Step 4: Simplified expression

After simplification, the expression becomes: ¬pp\neg p \lor p

Step 5: Apply the Law of Excluded Middle

The Law of Excluded Middle tells us that: ¬pp=True\neg p \lor p = \text{True} This is always true since either pp or ¬p\neg p will hold in every situation.

Step 6: Simplification

However, this is not yet fully aligned with ¬p\neg p. We must have misinterpreted some intermediate simplifications.

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Math Problem Analysis

Mathematical Concepts

Propositional Logic
Boolean Algebra
Logical Laws

Formulas

De Morgan's Law: ¬(p ∧ q) = ¬p ∨ ¬q
Distributive Law: A ∧ (B ∨ C) = (A ∧ B) ∨ (A ∧ C)
Absorption Law: p ∨ (p ∧ q) = p
Law of Excluded Middle: p ∨ ¬p = True

Theorems

De Morgan's Theorem
Distributive Theorem
Absorption Theorem
Law of Excluded Middle

Suitable Grade Level

Undergraduate or Advanced High School