And now let's think about our upper and lower bounds. Over that interval, this blue graph is our upper bound. And so we would subtract the lower bound from the upper bound. So we would have x to the fourth minus four x squared plus one. And from that, we will subtract x squared minus three dx. And in many other videos, we have talked about why you do this, why this makes sense to just subtract the lower graph from the upper graph when you're finding the area between them. But now we just have to evaluate this definite integral.