Answers:
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Explanation:
Recall the following
N = set of natural numbers
N = {1,2,3,4,5,6,...}
W = set of whole numbers
W = {0,1,2,3,4,5,6,...}
The sets N and W are nearly the same set, except for W has 0 involved, while N does not. The triple dots say that pattern goes on forever.
From those infinite sets, we form the two finite subsets A and B like so
A = {x : x < 6, x is in N}
A = {x such that x < 6 and x is a natural number}
A = {1,2,3,5}
B = {y : y < 4, y is in W}
B = {y such that y < 4 and y is a whole number}
B = {0,1,2,3}
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In short, we have these two finite sets
- A = {1,2,3,4,5}
- B = {0,1,2,3}
The notation A-B indicates we'll start with set A and kick out members of set B that are also in set A. This is known as set subtraction.
So we'll write out set A to get {1,2,3,4,5}
Then we cross off 1,2,3 in this set because these values are found in set B
We're left with {4,5}
Therefore A-B = {4,5}
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To compute B-A, we do the same idea but in reverse.
Start with set B
{0,1,2,3}
and erase the items 1,2,3 since they are found in set A
We then find that
B-A = {0}
Even though we have 1 item, don't forget about the curly braces to say we have a set. Any set that has exactly 1 item in it is considered a singleton set.
Keep in mind that the singleton {0} is not the empty set. The empty set would have nothing inside it and we would say { } instead.
