00:01
Hi, now we have to find the x coordinates of the critical points and determine if each relative maxima or minima or neither.
00:09
So now fx is given to us as 2x to the power 6 minus 3x to the power 4.
00:14
So for critical points we put f dash derivative x equal to 0.
00:18
So f derivative x will be equal to 12x to the power 5 minus 12x cube and we put equal to 0.
00:24
So this is 12x cube into x square minus 1 is equal to 0.
00:29
So from here we have either x is equal to 0 or x is equal to plus 1 or x is equal to minus 1.
00:35
So now we have the 3 critical points.
00:38
So we find f double derivative x.
00:40
So f double derivative x will be equal to 60x to the power 4 minus 36x square.
00:46
So f double derivative 0 is 0.
00:48
So double derivative test fails over here.
00:52
We will use single derivative test, first derivative test for this now.
00:56
F double derivative at minus 1 will be 60 minus 36 which is greater than 0.
01:02
So therefore this is the point of local minimum.
01:10
Now f double derivative at 1 is 60 minus 36 which is again greater than 0.
01:16
So again x is equal to 1 is the point of local minimum.
01:21
Now we have to check for 0...