The set {...} containing negative integers, zero, and positive integers is an example of which number system?

The set {...} containing negative integers, zero, and positive integers is an example of which number system?

• A. Integers
• B. Rational numbers
• C. Natural numbers
• D. Irrational numbers

Answer: (A)

You're being asked to identify what set includes every negative integer, zero, and every positive integer. That collection is exactly the integers: ..., -2, -1, 0, 1, 2, .... Natural numbers are the counting numbers (often starting at 1, sometimes including 0), so they would miss all negatives. Rational numbers include any fraction a/b with integers a and b (b ≠ 0), which is a bigger set than just the integers. Irrational numbers cannot be written as fractions of integers, so they’re not this set.

You're being asked to identify what set includes every negative integer, zero, and every positive integer. That collection is exactly the integers: ..., -2, -1, 0, 1, 2, .... Natural numbers are the counting numbers (often starting at 1, sometimes including 0), so they would miss all negatives. Rational numbers include any fraction a/b with integers a and b (b ≠ 0), which is a bigger set than just the integers. Irrational numbers cannot be written as fractions of integers, so they’re not this set.