00:02
So in this problem, we're given these two sets, a and b, in roster form.
00:08
And, of course, the first one in set builder is a set of x such that x equals 2n, where n is a natural number, right? and x is less than 20.
00:27
And the second one, b, right, is a set of x such that x equals n squared.
00:38
Where 1 is less than n is less than 20.
00:48
It's actually not even 20, right? 144 is 12 squared.
00:54
So this is actually 13.
01:00
Okay.
01:02
And we're asked to express the following sets in roster form.
01:10
So number one, it says a, union, b.
01:13
Well, so this is the set of all of these.
01:19
Combined, isn't it? just listing them all together.
01:24
Okay.
01:25
So this is the set of two, four.
01:29
Just start picking off the entries.
01:31
Two, four, which is already there.
01:35
And then six, eight, nine, ten.
01:41
Six, eight, nine, ten.
01:46
Twelve, fourteen, sixteen...