00:08
Okay, so we have two sets, h and k, that are subsets of a set g.
00:13
We want to show that their intersection, h intersect k, is a subset of that set g.
00:20
So let's start with what this means, saying they are subsets.
00:24
If it's a subset, that means that you could take any element of h.
00:29
So i'm just going to take a random one called x.
00:31
And that would mean, here, for any random element of h, that means that x is also an element of the set g.
00:45
Anything in h is also in g.
00:48
That also means the same thing for k.
00:51
So for any, i'll say y, just to make it different, y, that is inside an element of k, it's also going to be an element of g.
01:01
Anything in h, anything in k, those are also in g.
01:06
So then we want to show that their intersection is also a subset of g.
01:10
So let's consider what h intersect k means.
01:15
H intersect k is going to be a set with a bunch of elements.
01:20
So we're going to pick a random one.
01:28
Let's call this one a, again, just to be different from the x and y we've chosen before.
01:32
That's an element of that intersection...