00:01
Whenever you're asked to give a recursive definition, what it means to be recursive is that you need to know the previous number in order to get the next one.
00:12
So the two things you need to provide is the starting point.
00:18
So you need to provide the first term.
00:20
And then you need to provide the pattern.
00:23
So in our task here, where they give you the pattern, or they give you the numbers, 22, 15, 8, one, they do tell you it's arithmetic.
00:40
So the fact that they tell you it's arithmetic means that you're either adding or subtracting.
00:44
Well, in this case, you're subtracting the same number over and over again.
00:48
You're subtracting seven.
00:50
Subtracting seven.
00:51
I hope you can do that in your head, but if not, you can always take like the second number and subtract off the first and see that you would get negative seven.
00:59
You could do that with any number.
01:01
Okay, so i'm going to write this.
01:03
The pretty common way is writing you with t or, or a with a subscript...