Change of Order

Q. Changing the order of the integration in the double integral $I={\int }_0^8{\int }_{x/4}^{2}f(x,y)dydx$ leads to $I={\int }_r^s{\int }_p^{q}f(x,y)dxdy$. What is $q$?

1. $4y$
2. $16y^2$
3. $x$
4. $8$

Q. The double integral ${\int }_0^a{\int }_0^{y}f(x,y)dxdy$ is equivalent to

1. ${\int }_0^x{\int }_0^{y}f(x,y)dxdy$
2. ${\int }_0^a{\int }_x^{y}f(x,y)dxdy$
3. ${\int }_0^a{\int }_x^{a}f(x,y)dydx$
4. ${\int }_0^a{\int }_x^{a}f(x,y)dydy$