00:01
For this problem, our function is 2x cubed minus 3x squared minus 12x plus 1.
00:05
So our first step here will be to take the first derivative, which will give us 6x squared minus 6x minus 12.
00:15
We can simplify this by factoring out the 6 from the expression, writing this as x squared minus x minus 2, or further factoring as 6 times x plus 1 times x minus 1.
00:30
Minus 2.
00:33
Which then means that we can find that our critical points, critical points will be found at x equals negative 1 and positive 2.
00:45
Then finding our second derivative, f double prime of x, that will be equal to 12x minus 6.
00:52
So if we want to determine concavity, if we want concave up, we want 12x minus 6 to be greater than 0, which then means we want 12x to be greater than 6.
01:06
So x must be greater than 1 over 2...