Simplify the following union and/or intersection. ( −17, 1] ∩ [ 1, 17 )

Question

I don't know how to solve this question at all. I was never taught this in high school.

Answer 1

The inverted U means intersection, which means: what set is in common to the two sets in brackets?

In one set we have just -17 and 1 and in the other just 1 and 17. The only element they have in common is 1 so { 1 } is the intersection set, a set with one element, the number 1. 17 and -17 are two different quantities, although they have the same magnitude. That was just to confuse you! But you are wise enough not to be fooled by that trick!