00:01
Okay, this problem is just examples, so i'm just going to go through the examples and explain it to you.
00:08
The first question we're given a and b sets a and b, and i want to know first of all, is a a subset of b? in order for a to be a subset of b, every element in a has to be in b.
00:27
So in a, i've got a 1, and i've got a 1 there.
00:31
I've got a 2, and i've got a 2 there.
00:34
I've got a 3, and i've got a 3 there.
00:36
So yes, a is a subset of b.
00:40
Next it says, is b a subset of a? well in this case, everything in b has to be in a.
01:02
Alright, in b, i've got 1, and there's a 1.
01:06
I've got 2, and there's a 2.
01:08
I've got 3, and there's a 3.
01:10
But i've got a 4 and a 5 that's not there.
01:15
So no.
01:18
So you've got to look at the first set first, and everything in that set has to be in the second one.
01:26
Okay, on example 2, we're supposed to give all the possible subsets of a, b.
01:37
Okay, so we're supposed to list all the subsets.
01:40
First of all, always start with the empty set.
01:44
Okay, and there's a systematic way to go about this.
01:48
This is the set that contains no elements.
01:53
So now let's list all the sets that contain one element, not one set, one element.
02:03
Okay, so it'd be a and then b.
02:10
Alright, and then two elements.
02:12
Well there's only one, and it's ab...