Which interval represents all real numbers?
Answer and explanation
Correct answer: (-∞, ∞)
The set of all real numbers extends without bound in both the negative and positive directions. In interval notation it is written as (-∞, ∞), which represents every real number x satisfying -∞ < x < ∞. Infinity is not an actual real number or endpoint, so it is always written with round brackets, never square brackets. Therefore, option A is correct.
Frequently asked questions
What is the correct answer to this question?
(-∞, ∞)
Why is this the correct answer?
The set of all real numbers extends without bound in both the negative and positive directions. In interval notation it is written as (-∞, ∞), which represents every real number x satisfying -∞ < x < ∞. Infinity is not an actual real number or endpoint, so it is always written with round brackets, never square brackets. Therefore, option A is correct.
Which subject and chapter does this question cover?
This is a Class 10 Mathematics question. Chapter: Sets. Topic: Sets and their representations.
