Exam-style question
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Which set is represented by the set-builder notation A = {x | x ∈ ℕ ∧ x ≥ 1}?.
- A.The natural numbers greater than or equal to 1
- B.The natural numbers less than or equal to 1
- C.The real numbers greater than or equal to 1
- D.The natural numbers greater than 1 only
Model answer
What a good answer should say
- The natural numbers greater than or equal to 1
Explanation
Why this works
The symbol | means 'such that', ∈ means 'is a member of', and ∧ means 'AND'. Therefore, the set contains natural numbers x where x is at least 1: {1, 2, 3, 4, …}.
Common mistake
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