The set that is ALWAYS rational is Whole Numbers.
Explanation:
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Whole Numbers: This set includes 0, 1, 2, 3, and so on. Whole numbers can be expressed as fractions where the denominator is 1 (e.g., 3 can be written as \( \frac{3}{1} \)), which makes them rational numbers.
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Negative Numbers: While many negative numbers are rational (like -1, -2, etc.), not all negative numbers are rational. For example, negative square roots of non-perfect squares (like \(-\sqrt{2}\)) are irrational.
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Non Terminating Decimals: Non-terminating decimals can be either rational or irrational. For example, the decimal representation of \( \frac{1}{3} = 0.333...\) is non-terminating and rational, while \(\pi\) (approximately 3.14159...) is an example of a non-terminating decimal that is irrational.
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Decimals: This category includes both terminating (like 0.5) and non-terminating decimals (like 0.333...). Terminating decimals are rational, but non-terminating decimals can be either rational or irrational.
Thus, whole numbers are the only set listed that is always rational.