Determine Whether the Given Argument Is Valid or Invalid C) Invalid

question 95

Multiple Choice

determine whether the given argument is valid or invalid. If it is invalid, select a counterexample.
-1. (?x) (Ax ? Bx) ? (?x) Cx
2) (?x) (Ax • ?Bx)
3) (?x) (Dx ? Bx) / (?x) (Dx ? Cx)

• A) Valid
• B) Invalid. Counterexample in a domain of 2 members, in which:
• \[\begin{array} { l l l l }
• \text { Aa: True } & \text { Ba: False } & \text { Ca: False } & \text { Da: False } \\
• \text { Ab: False} &\text { Bb: True } &\text {Cb: False }&\text { Db: True } \\
• \end{array}\]
• C) Invalid. Counterexample in a domain of 2 members, in which:
• \[\begin{array} { l l l l }
• \text { Aa: True } & \text { Ba: False } & \text { Ca: False } & \text { Da: False } \\
• \text { Ab: True} &\text { Bb: True } &\text {Cb: True }&\text { Db: True } \\
• \end{array}\]
• D) Invalid. Counterexample in a domain of 2 members, in which:
• \[\begin{array} { l l l l }
• \text { Aa: False} & \text { Ba: False } & \text { Ca: False } & \text { Da: False } \\
• \text { Ab: False} &\text { Bb: True } &\text {Cb: False }&\text { Db: True } \\
• \end{array}\]
• E) Invalid. Counterexample in a domain of 2 members, in which:
• Aa: True Ba: False Ca: False Da: False Ab: True Bb: False Cb: False Db: True

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Definitions:

Revoke

To officially cancel or withdraw an offer, license, right, or permission that has been granted.

Letter of Credit

A financial document issued by a bank guaranteeing a buyer's payment to a seller within a specified timeframe and under agreed conditions.

Formal Contract

A contract that by law requires a specific form, such as being executed under seal, to be valid.

Unilateral Contracts

Contracts in which one party makes a promise in exchange for the other's performance, which fulfills the contract.