00:01
We are given the graph of f prime.
00:03
We know that f is increasing where the derivative f prime is positive, so greater than zero.
00:14
So we see that f prime is positive here, so from negative infinity to negative three, the x values, and also here.
00:32
So that is from positive one to positive infinity.
00:40
And f is decreasing where f prime is negative, so less than zero.
00:51
I see that f prime is negative in this region, so that is from negative three to positive one.
01:06
Also, i should note that when you are entering your solutions, you will use a comma instead of a u.
01:15
Also, f will have extrema at f equals c, where f prime of c equals zero.
01:32
And f prime before c, so i'll call that less than c, has the opposite sign.
01:40
So i'll just write this as the sign of f prime of c is opposite the sign of f prime of after c.
01:53
Okay, so that's greater than c.
01:57
So i hope that's not too confusing.
01:59
I will show you this.
02:00
So we see that there is a point here, where f prime is zero.
02:07
And before that point, f prime is positive.
02:11
And after that point, f prime is negative.
02:14
So that means f prime changes sign at this point.
02:18
So there will be an extrema at this point, and it will be at x equals negative three.
02:26
There is also another point where f prime is zero, that is here.
02:32
Okay, we see that before that point, f prime is negative...