ELI5: Explain Like I'm 5

Integral of inverse functions

Ok kiddo, imagine that you have two friends, let's call them X and Y. X and Y are like opposites - when X goes up, Y goes down, and when X goes down, Y goes up. They're like a see-saw!

Now, let's say you want to find out how much Y moves when X moves a certain distance. To work this out, you'll need to use something called the inverse function. The inverse function basically does the opposite of what the original function does - so if the original function takes X and gives you Y, the inverse function takes Y and gives you X. It's like a magic trick!

But you can't just use the inverse function by itself, because you need to find out how far Y moves when X moves a certain distance. So that's where something called the integral comes in. The integral helps you find the area under a curve (which is a fancy way of saying the space between the curve and the X-axis).

So, to find out how much Y moves when X moves a certain distance, you need to use the inverse function and the integral together. You start by finding the inverse function, which gives you the equation for Y in terms of X. Then, you use the integral to find the area under the curve of the inverse function.

This might sound complicated, but it's a bit like counting the number of squares in a picture. You just divide the picture up into lots of little squares, count them all up, and then you know how much area there is!

Once you know the area under the curve of the inverse function, you can use that information to work out how much Y moves when X moves a certain distance. Basically, the area under the curve tells you how much Y has changed overall, and you can use that to figure out how much Y moves for a specific change in X.

And that's it! By using the inverse function and the integral together, you can work out how much Y moves when X moves a certain distance. Isn't maths cool?