Question

Change the order of the integration in
${\int }_0^a{\int }_0^{y}f\left(x,y\right)dxdy$

Answer 1

${\int }_0^a{\int }_o^{y}f(x,y)dxdx={\int }_o^a{\int }_{a-x}^{a}f(x,y)dydx$