# How can I prove a contradiction follows from P <-> Q and P -> ~Q?

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## How do you prove a contradiction?

To prove something by contradiction, we assume that what we want to prove is not true, and then show that the consequences of this are not possible. That is, the consequences contradict either what we have just assumed, or something we already know to be true (or, indeed, both) – we call this a contradiction.

## What is the contradiction of P -> Q?

p and q are integers, ● q ≠ 0, and ● p and q have no common divisors other than ±1. A number that is not rational is called irrational. Proof: By contradiction; assume √2is rational. Then there exists integers p and q such that q ≠ 0, p / q = √ , and p and q have no common divisors other than 1 and -1.

## Which method of proof uses contradiction to prove a statement?

Nonconstructive Proof: Assume no c exists that makes P(c) true and derive a contradiction. In other words, use a proof by contradiction.

## What is an example of contradiction?

A contradiction is a situation or ideas in opposition to one another. Declaring publicly that you are an environmentalist but never remembering to take out the recycling is an example of a contradiction. A “contradiction in terms” is a common phrase used to describe a statement that contains opposing ideas.

## What is proof by contradiction explain it with example?

In logic and mathematics, proof by contradiction is a form of proof that establishes the truth or the validity of a proposition, by showing that assuming the proposition to be false leads to a contradiction.

## Which method is used to prove statements of the form if/p then q or p implies q?

The best approach in doing a proof by contrapositive is to restate the original problem in the form, “If p, then q”. The contrapositive is then, “If not q, then not p”.