This means, or this would be a byproduct, or this would cause the second derivative to be negative. Our slope is decreasing. And this would be our second derivative. Our second derivative is 0. If your slope isn't changing, if your slope is constant, if your first derivative is constant, your second derivative is going to be 0. So let's just see what our second derivative is at our initial condition, and then we'll have a pretty good sense of whether we have an overestimate or an underestimate for part A. So let's just figure out what our second derivative is at time 0.