So it can never get to negative three. So if anything's ever going to get to negative three, it's going to have to be this part of the derivative or this part of the derivative definition. So it's going to have to be this thing right over here. And hopefully there's some values of x greater than zero where this thing right over here is equal to negative three. So let's try it out. Negative four e to the negative four x needs to be equal to negative three. We can divide both sides by negative four.