Question

Which of the following represent the collection of all the real numbers on a number line?

• A. $(-\infty ,\infty ]$
• B. $(-\infty ,\infty )$
• C. $[-\infty ,\infty ]$
• D. $[-\infty ,\infty )$

Answer 1

The correct option is B $(-\infty ,\infty )$

Infinities are not well defined. So we cannot include that with closed brackets. So the answer is $(-\infty ,\infty )$.