00:01
Let's do y equals negative x to the fourth plus 31x cubed minus 340x squared plus 1525x minus 2190.
00:19
Let's find the derivative of this.
00:22
So this is going to be negative 4x cubed plus 31 times 3 is 93.
00:32
X squared minus is going to be 680x plus 1525.
00:41
Okay, so this is the first derivative.
00:43
We could set this equal to 0.
00:45
So if we set this equal to 0, we could find the critical point.
00:59
Use the calculator here because this is a little complex.
01:02
So i got 4 .32515, i got 8 .28329, and i got 10 .64154.
01:22
And so let's find the y's at these x values.
01:27
So i'm going to call this x1, x2, x3.
01:30
So at this point here, we have 203 .76876.
01:38
Say at x2, we get 24 .45969...