00:01
With this problem, the problem with doing the second derivative test is we might get a value that doesn't actually work.
00:12
So in order to find if it's a critical number, we find the derivative, which is going to be the power rule you multiply in front, and then subtract one from your exponent.
00:26
And the theme is that you would set this equal to zero, and you could factor out a 6x squared from that.
00:32
You would be left with 2x minus 1 equals 0.
00:37
So we get critical numbers at 0, but this actually has a multiplicity of 2 because of the squared, and then also x equals 1 1 half.
00:46
So if you were to try, maybe you create a number line and you plugged in certain numbers, let's say at 0 and then here's 1 half, but maybe you plug in a negative number, a number between 0 and 1 half, and a number to the right.
01:01
Well, if you start to plug that in, any negative number when you square it is positive.
01:07
And then over here, you get a negative.
01:09
And negative minus one and so be negative.
01:12
Well, a positive times a negative is negative.
01:14
And that's telling me that we're decreasing...