To reverse the order of integration of $$\int_{x_\text{min}}^{x_\text{max}} \int_{y_\text{min}(x)}^{y_\text{max}(x)} f(x,y) dy dx,$$
- Sketch the two dimensional region of integration,
- Find the minimum and maximum values of $y$,
- For each $y$, find the minimum and maximum values of $x$,
- Rewrite the integral as $$\int_{y_\text{min}}^{y_\text{max}} \int_{x_\text{min}(y)}^{x_\text{max}(y)} f(x,y) dx dy$$