And so let's do that. F of six minus f of four, all of that over six minus four is equal to seven minus three over two, which is equal to two. So two not equal to five, so mean value theorem doesn't apply. Apply. All right, let's, I'll put an exclamation mark there for emphasis. All right, let's do the next part. Can we use the mean value theorem to say that the equation f prime of x is equal to negative one has a solution, and now the interval is from zero to two.