Question

If T = {integers} and subset W = {positive integers}, what is W′?

Answer 1

If T = {integers} and subset W = {positive integers}, what is W′?

Answer 2

It all depends what you consider your universal set.

Answer 3

If A = {relish, onion, cheese} and B = {chili, mustard, cheese}, what is A B?

Answer 4

Assuming the universal set is T,
Since all integers can be thought of as either negative, positive, or zero, then
T = set of all negative integers U set of all positive integers U {0}. Since W = set of all positive integers, and the following must be true,
\[W \cup W' = T\]
Then it follows through logic I won't both to formally show,
\[W' =(allnegintegers) \cup {0}\],
Or more elegantly,
\[W' = \mathbb{R} \subset {x: x \le0}\]

Answer 5

Whoops!
That should be \[Z\] not \[{R}\]

Answer 6

...
generally (and basically)
W' is a fancy way of saying NOT W
meaning all things NOT in W :)

Answer 7

That's a good way of putting it in words, where "all things" is the universal set.