# Thread: Double integral problem

1. ## Double integral problem

I ahve the question $\displaystyle \int\int_D f(x,y) dxdy$, where $\displaystyle f(x,y)=xy^2$ and D is the region in the first quadrant D bounded by the curves $\displaystyle y = x^2$ and $\displaystyle x = y^2$.

And i think im right in saying that this is the same as
$\displaystyle \int^{\sqrt{x}}_{-\sqrt{x}} \int^{\sqrt{y}}_{-\sqrt{y}} xy^2 dxdy$
but when i do the first integral it equals 0 so i dont know what to do with the next

2. Your limits are wrong
The integral is:
$\displaystyle \int_{0}^{1} \int_{y^2}^{\sqrt{y}} xy^2 \, dx \, dy$

For the double integral over general region, the limits of the outer integral should be constants ..

3. oh right ok but how do you know what the integral limit are supposed to be?

4. What is the first step to solve a double integral over general region?

5. oh i get it know i watched
YouTube - Calculating Double Integrals over General Regions
and i was just thinking about the limits wrong thanks