# Math Help - Changing order of integration?

1. ## Changing order of integration?

In The integral

$\int_1^{2} dx \int_{2-x}^{\sqrt{2x-x^2}} f(x,y)dy$

Change the order of integration.

Can any1 tell me how to do this?
i think y goes from 0 to 1 but i dont know how to do x.

2. What's y doing? It's going from the lower curve $y=2-x$ to the upper curve $y=\sqrt{2x-x^2}$. We then form the Riemann sum of that from x=1 to x=2. It helps to draw the curves. When we switch the order, integrating with respect to x. Now what is x doing? Well, x will be going across the same curves but in terms of x: from $x=2-y$ to $x=1-\sqrt{1-y^2}$ (complete the square). And then we form the Riemann sum of that and let y go from 0 to 1.

$\int_0^1\int_{2-y}^{1-\sqrt{1-y^2}} fdxdy$