And so the interval that we care about, the interval over which we're decreasing is just x is less than 5 1⁄2. And we can see that by graphing the function. I graphed it on Desmos. And you can see here that the function is decreasing from negative infinity, it's decreasing at a slower and slower rate, we get to zero, still decreasing to the left of zero, and then it continues to decrease to the right of zero. So any x value to the left of zero, the value of the function is going to be larger than f of zero. And x to the right of zero, the value of the function is going to be less than the function at zero. So it's actually decreasing through zero, even though the slope of the tangent line at zero is zero, even though it's non-negative.