The set of integers is always rational.
Rational numbers are defined as numbers that can be expressed as the quotient of two integers, where the denominator is not zero. Since integers can be written as fractions (e.g., \(5\) can be expressed as \(\frac{5}{1}\)), they are always rational.
To clarify the other sets:
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Positive numbers: This set includes both rational (like \(1\) or \(0.5\)) and irrational numbers (like \(\sqrt{2}\)) and thus is not always rational.
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Negative numbers: Similarly, this set can include both rational (like \(-1\) or \(-0.5\)) and irrational numbers (like \(-\sqrt{2}\)) and is not restricted to rational numbers.
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Decimals: This set includes both terminating decimals (which are rational, like \(0.5\)) and non-terminating, non-repeating decimals (which are irrational, like \( \pi\)) and is thus not always rational.
So, the set of integers is the only one in your list that is always rational.