Chapter 15.1, Problem 57E

Use a computer algebra system to compute the iterated integrals

${\displaystyle {\int }_0^1{\displaystyle {\int }_0^1\frac{x-y}{{(x+y)}^3}}}dydx$ and ${\displaystyle {\int }_0^1{\displaystyle {\int }_0^1\frac{x-y}{{(x+y)}^3}}}dxdy$

Do the answers contradict Fubini's Theorem? Explain what is happening.