Question

Which of the following has no solution?
{x | x < 0} and {x | x > 0}
{x | x ≤ 0} and {x | x ≥ 0}
{x | x ≤ 0} or {x | x ≥ 0}

Answer 1

The first one. It's because the other ones can equal 0. But this one says the a number is greater than 0 and less than 0. How can a number be both greater and less than 0?