00:01
So you definitely need to be careful on a problem like this because they're giving you the graph of the derivative.
00:07
So i'm going to point out negative 2, negative 1, 1, and 3.
00:14
I think those are the only points i really need to know.
00:17
Well, 4 i also need to know.
00:20
So if i'm reading this correctly, we have a max.
00:23
We have a 0, an arrow down.
00:26
We have a minimum and a 0 at 1.
00:29
And then an open circle, and then another open circle, and then another 0 at 4 with an open circle at 5.
00:41
I guess i should clarify that as well.
00:43
So if f is increasing, that's because f prime is positive.
00:53
Double -edded arrow.
00:55
So we can answer this question on the interval from negative 2 to 1.
01:01
I'm going to put a little break there because it's actually equal 0 at 1.
01:07
And then 1 to 3, where 3 is undefined.
01:11
And then from 3 to 4.
01:15
So if i flip that around, where is f decreasing? so again, a double -headed arrow here.
01:23
F prime would be negative.
01:25
And that interval would be, well, the arrowhead would be from negative infinity to negative 3, excuse me, negative 2, as well as 4 to 5 because it's an open circle at 5...