So she's basing this just on the fact that the second derivative is zero when x is equal to two. She's basing this just on the fact that f prime prime of two is equal to zero. Now I have a problem with this because the fact that your second derivative is zero at x equals two, that makes two a nice candidate to check out, but you can't immediately say that we have an inflection point there. Remember, an inflection point is where we go from being concave upwards to concave downwards or concave downwards to concave upwards. And speaking in the language of the second derivative, it means that the second derivative changes signs as we go from below x equals two to above x equals two. But we have to test that because it's not necessarily always the case. So let's actually test it.